move to new libgnunetpq library, simplifying libtalerpq

6 files changed, 595 insertions, 1385 deletions

diff --git a/src/pq/Makefile.am b/src/pq/Makefile.am
index 2187d494b..810aa47b3 100644
--- a/src/pq/Makefile.am
+++ b/src/pq/Makefile.am
@@ -12,8 +12,8 @@ lib_LTLIBRARIES = \
   libtalerpq.la
 
 libtalerpq_la_SOURCES = \
-  db_pq.c \
-  pq_helper.c
+  pq_query_helper.c \
+  pq_result_helper.c
 
 libtalerpq_la_LIBADD = \
   $(top_builddir)/src/util/libtalerutil.la  \
@@ -36,5 +36,7 @@ test_pq_SOURCES = \
 test_pq_LDADD = \
   libtalerpq.la \
   $(top_builddir)/src/util/libtalerutil.la  \
-  -lgnunetutil -ljansson \
+  -lgnunetpq \
+  -lgnunetutil \
+  -ljansson \
   -lpq $(XLIB)
diff --git a/src/pq/db_pq.c b/src/pq/db_pq.c
deleted file mode 100644
index 59a1db022..000000000
--- a/src/pq/db_pq.c
+++ /dev/null
@@ -1,883 +0,0 @@
-/*
-  This file is part of TALER
-  Copyright (C) 2014, 2015 GNUnet e.V.
-
-  TALER is free software; you can redistribute it and/or modify it under the
-  terms of the GNU General Public License as published by the Free Software
-  Foundation; either version 3, or (at your option) any later version.
-
-  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
-  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
-
-  You should have received a copy of the GNU General Public License along with
-  TALER; see the file COPYING.  If not, If not, see <http://www.gnu.org/licenses/>
-*/
-/**
- * @file pq/db_pq.c
- * @brief helper functions for libpq (PostGres) interactions
- * @author Sree Harsha Totakura <sreeharsha@totakura.in>
- * @author Florian Dold
- * @author Christian Grothoff
- */
-#include "platform.h"
-#include <gnunet/gnunet_util_lib.h>
-#include "taler_pq_lib.h"
-
-
-/**
- * Execute a prepared statement.
- *
- * @param db_conn database connection
- * @param name name of the prepared statement
- * @param params parameters to the statement
- * @return postgres result
- */
-PGresult *
-TALER_PQ_exec_prepared (PGconn *db_conn,
-                        const char *name,
-                        const struct TALER_PQ_QueryParam *params)
-{
-  unsigned int len;
-  unsigned int i;
-
-  /* count the number of parameters */
-  i = 0;
-  len = 0;
-  while (TALER_PQ_QF_END != params[i].format)
-  {
-    const struct TALER_PQ_QueryParam *x = &params[i];
-
-    switch (x->format)
-    {
-    case TALER_PQ_QF_FIXED_BLOB:
-    case TALER_PQ_QF_VARSIZE_BLOB:
-      len++;
-      break;
-    case TALER_PQ_QF_AMOUNT_NBO:
-    case TALER_PQ_QF_AMOUNT:
-      len += 3;
-      break;
-    case TALER_PQ_QF_RSA_PUBLIC_KEY:
-    case TALER_PQ_QF_RSA_SIGNATURE:
-    case TALER_PQ_QF_TIME_ABSOLUTE:
-    case TALER_PQ_QF_UINT16:
-    case TALER_PQ_QF_UINT32:
-    case TALER_PQ_QF_UINT64:
-    case TALER_PQ_QF_JSON:
-      len++;
-      break;
-    default:
-      /* format not supported */
-      GNUNET_assert (0);
-      break;
-    }
-    i++;
-  }
-
-  /* new scope to allow stack allocation without alloca */
-  {
-    /* Scratch buffer for temporary storage */
-    void *scratch[len];
-    /* Parameter array we are building for the query */
-    void *param_values[len];
-    int param_lengths[len];
-    int param_formats[len];
-    unsigned int off;
-    /* How many entries in the scratch buffer are in use? */
-    unsigned int soff;
-    PGresult *res;
-
-    i = 0;
-    off = 0;
-    soff = 0;
-    while (TALER_PQ_QF_END != params[i].format)
-    {
-      const struct TALER_PQ_QueryParam *x = &params[i];
-
-      switch (x->format)
-      {
-      case TALER_PQ_QF_FIXED_BLOB:
-      case TALER_PQ_QF_VARSIZE_BLOB:
-        param_values[off] = (void *) x->data;
-        param_lengths[off] = x->size;
-        param_formats[off] = 1;
-        off++;
-        break;
-      case TALER_PQ_QF_AMOUNT_NBO:
-        {
-          const struct TALER_Amount *amount = x->data;
-
-          param_values[off] = (void *) &amount->value;
-          param_lengths[off] = sizeof (amount->value);
-          param_formats[off] = 1;
-          off++;
-          param_values[off] = (void *) &amount->fraction;
-          param_lengths[off] = sizeof (amount->fraction);
-          param_formats[off] = 1;
-          off++;
-          param_values[off] = (void *) amount->currency;
-          param_lengths[off] = strlen (amount->currency);
-          param_formats[off] = 1;
-          off++;
-        }
-        break;
-      case TALER_PQ_QF_AMOUNT:
-        {
-          const struct TALER_Amount *amount_hbo = x->data;
-          struct TALER_AmountNBO *amount;
-
-          amount = GNUNET_new (struct TALER_AmountNBO);
-          scratch[soff++] = amount;
-          TALER_amount_hton (amount,
-                             amount_hbo);
-          param_values[off] = (void *) &amount->value;
-          param_lengths[off] = sizeof (amount->value);
-          param_formats[off] = 1;
-          off++;
-          param_values[off] = (void *) &amount->fraction;
-          param_lengths[off] = sizeof (amount->fraction);
-          param_formats[off] = 1;
-          off++;
-          param_values[off] = (void *) amount->currency;
-          param_lengths[off] = strlen (amount->currency);
-          param_formats[off] = 1;
-          off++;
-        }
-        break;
-      case TALER_PQ_QF_RSA_PUBLIC_KEY:
-        {
-          const struct GNUNET_CRYPTO_rsa_PublicKey *rsa = x->data;
-          char *buf;
-          size_t buf_size;
-
-          buf_size = GNUNET_CRYPTO_rsa_public_key_encode (rsa,
-                                                          &buf);
-          scratch[soff++] = buf;
-          param_values[off] = (void *) buf;
-          param_lengths[off] = buf_size - 1; /* DB doesn't like the trailing \0 */
-          param_formats[off] = 1;
-          off++;
-        }
-        break;
-      case TALER_PQ_QF_RSA_SIGNATURE:
-        {
-          const struct GNUNET_CRYPTO_rsa_Signature *sig = x->data;
-          char *buf;
-          size_t buf_size;
-
-          buf_size = GNUNET_CRYPTO_rsa_signature_encode (sig,
-                                                         &buf);
-          scratch[soff++] = buf;
-          param_values[off] = (void *) buf;
-          param_lengths[off] = buf_size - 1; /* DB doesn't like the trailing \0 */
-          param_formats[off] = 1;
-          off++;
-        }
-        break;
-      case TALER_PQ_QF_TIME_ABSOLUTE:
-        {
-          const struct GNUNET_TIME_Absolute *at_hbo = x->data;
-          struct GNUNET_TIME_AbsoluteNBO *at_nbo;
-
-          at_nbo = GNUNET_new (struct GNUNET_TIME_AbsoluteNBO);
-          scratch[soff++] = at_nbo;
-          *at_nbo = GNUNET_TIME_absolute_hton (*at_hbo);
-          param_values[off] = (void *) at_nbo;
-          param_lengths[off] = sizeof (struct GNUNET_TIME_AbsoluteNBO);
-          param_formats[off] = 1;
-          off++;
-        }
-        break;
-      case TALER_PQ_QF_UINT16:
-        {
-          const uint16_t *u_hbo = x->data;
-          uint16_t *u_nbo;
-
-          u_nbo = GNUNET_new (uint16_t);
-          scratch[soff++] = u_nbo;
-          *u_nbo = htons (*u_hbo);
-          param_values[off] = (void *) u_nbo;
-          param_lengths[off] = sizeof (uint16_t);
-          param_formats[off] = 1;
-          off++;
-        }
-        break;
-      case TALER_PQ_QF_UINT32:
-        {
-          const uint32_t *u_hbo = x->data;
-          uint32_t *u_nbo;
-
-          u_nbo = GNUNET_new (uint32_t);
-          scratch[soff++] = u_nbo;
-          *u_nbo = htonl (*u_hbo);
-          param_values[off] = (void *) u_nbo;
-          param_lengths[off] = sizeof (uint32_t);
-          param_formats[off] = 1;
-          off++;
-        }
-        break;
-      case TALER_PQ_QF_UINT64:
-        {
-          const uint64_t *u_hbo = x->data;
-          uint64_t *u_nbo;
-
-          u_nbo = GNUNET_new (uint64_t);
-          scratch[soff++] = u_nbo;
-          *u_nbo = GNUNET_htonll (*u_hbo);
-          param_values[off] = (void *) u_nbo;
-          param_lengths[off] = sizeof (uint64_t);
-          param_formats[off] = 1;
-          off++;
-        }
-        break;
-      case TALER_PQ_QF_JSON:
-        {
-          const json_t *json = x->data;
-          char *str;
-
-          str = json_dumps (json, JSON_COMPACT);
-          GNUNET_assert (NULL != str);
-          scratch[soff++] = str;
-          param_values[off] = (void *) str;
-          param_lengths[off] = strlen (str);
-          param_formats[off] = 1;
-          off++;
-        }
-        break;
-      default:
-        /* format not supported */
-        GNUNET_assert (0);
-        break;
-      }
-      i++;
-    }
-    GNUNET_assert (off == len);
-    res = PQexecPrepared (db_conn,
-                          name,
-                          len,
-                          (const char **) param_values,
-                          param_lengths,
-                          param_formats,
-                          1);
-    for (off = 0; off < soff; off++)
-      GNUNET_free (scratch[off]);
-    return res;
-  }
-}
-
-
-/**
- * Free all memory that was allocated in @a rs during
- * #TALER_PQ_extract_result().
- *
- * @param rs reult specification to clean up
- */
-void
-TALER_PQ_cleanup_result (struct TALER_PQ_ResultSpec *rs)
-{
-  unsigned int i;
-
-  for (i=0; TALER_PQ_RF_END != rs[i].format; i++)
-  {
-    switch (rs[i].format)
-    {
-    case TALER_PQ_RF_VARSIZE_BLOB:
-      {
-	void **dst = rs[i].dst;
-	if (NULL != *dst)
-	{
-	  GNUNET_free (*dst);
-	  *dst = NULL;
-	  *rs[i].result_size = 0;
-	}
-	break;
-      }
-    case TALER_PQ_RF_RSA_PUBLIC_KEY:
-      {
-	void **dst = rs[i].dst;
-	if (NULL != *dst)
-	{
-	  GNUNET_CRYPTO_rsa_public_key_free (*dst);
-	  *dst = NULL;
-	}
-	break;
-      }
-    case TALER_PQ_RF_RSA_SIGNATURE:
-      {
-	void **dst = rs[i].dst;
-	if (NULL != *dst)
-	{
-	  GNUNET_CRYPTO_rsa_signature_free (*dst);
-	  *dst = NULL;
-	}
-      }
-      break;
-    default:
-      break;
-    }
-  }
-}
-
-
-/**
- * Extract results from a query result according to the given specification.
- * If colums are NULL, the destination is not modified, and #GNUNET_NO
- * is returned.
- *
- * @param result result to process
- * @param[in,out] rs result specification to extract for
- * @param row row from the result to extract
- * @return
- *   #GNUNET_YES if all results could be extracted
- *   #GNUNET_NO if at least one result was NULL
- *   #GNUNET_SYSERR if a result was invalid (non-existing field)
- */
-int
-TALER_PQ_extract_result (PGresult *result,
-                         struct TALER_PQ_ResultSpec *rs,
-                         int row)
-{
-  unsigned int i;
-  int had_null = GNUNET_NO;
-
-  for (i=0; TALER_PQ_RF_END != rs[i].format; i++)
-  {
-    struct TALER_PQ_ResultSpec *spec;
-
-    spec = &rs[i];
-    switch (spec->format)
-    {
-    case TALER_PQ_RF_FIXED_BLOB:
-    case TALER_PQ_RF_VARSIZE_BLOB:
-      {
-        size_t len;
-        const char *res;
-        void *dst;
-        int fnum;
-
-        fnum = PQfnumber (result,
-                          spec->fname);
-        if (fnum < 0)
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Field `%s' does not exist in result\n",
-                      spec->fname);
-          return GNUNET_SYSERR;
-        }
-        if (PQgetisnull (result,
-                         row,
-                         fnum))
-        {
-          had_null = GNUNET_YES;
-          continue;
-        }
-
-        /* if a field is null, continue but
-         * remember that we now return a different result */
-        len = PQgetlength (result,
-                           row,
-                           fnum);
-        if ( (0 != spec->dst_size) &&
-             (spec->dst_size != len) )
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Field `%s' has wrong size (got %u, expected %u)\n",
-                      spec->fname,
-                      (unsigned int) len,
-                      (unsigned int) spec->dst_size);
-          TALER_PQ_cleanup_result (rs);
-          return GNUNET_SYSERR;
-        }
-        res = PQgetvalue (result,
-                          row,
-                          fnum);
-        GNUNET_assert (NULL != res);
-        if (0 == spec->dst_size)
-        {
-          if (NULL != spec->result_size)
-            *spec->result_size = len;
-          spec->dst_size = len;
-          dst = GNUNET_malloc (len);
-          *((void **) spec->dst) = dst;
-        }
-        else
-          dst = spec->dst;
-        memcpy (dst,
-                res,
-                len);
-        break;
-      }
-    case TALER_PQ_RF_AMOUNT_NBO:
-      {
-        char *val_name;
-        char *frac_name;
-        char *curr_name;
-        const char *name = spec->fname;
-        int ret;
-
-        GNUNET_assert (NULL != spec->dst);
-        GNUNET_assert (sizeof (struct TALER_AmountNBO) ==
-                       spec->dst_size);
-        GNUNET_asprintf (&val_name,
-                         "%s_val",
-                         name);
-        GNUNET_asprintf (&frac_name,
-                         "%s_frac",
-                         name);
-        GNUNET_asprintf (&curr_name,
-                         "%s_curr",
-                         name);
-        ret = TALER_PQ_extract_amount_nbo (result,
-                                           row,
-                                           val_name,
-                                           frac_name,
-                                           curr_name,
-                                           spec->dst);
-        GNUNET_free (val_name);
-        GNUNET_free (frac_name);
-        GNUNET_free (curr_name);
-        if (GNUNET_SYSERR == ret)
-          return GNUNET_SYSERR;
-        if (GNUNET_OK != ret)
-          had_null = GNUNET_YES;
-        break;
-      }
-    case TALER_PQ_RF_AMOUNT:
-      {
-        char *val_name;
-        char *frac_name;
-        char *curr_name;
-        const char *name = spec->fname;
-        int ret;
-
-        GNUNET_assert (NULL != spec->dst);
-        GNUNET_assert (sizeof (struct TALER_Amount) ==
-                       spec->dst_size);
-        GNUNET_asprintf (&val_name,
-                         "%s_val",
-                         name);
-        GNUNET_asprintf (&frac_name,
-                         "%s_frac",
-                         name);
-        GNUNET_asprintf (&curr_name,
-                         "%s_curr",
-                         name);
-        ret = TALER_PQ_extract_amount (result,
-                                       row,
-                                       val_name,
-                                       frac_name,
-                                       curr_name,
-                                       spec->dst);
-        GNUNET_free (val_name);
-        GNUNET_free (frac_name);
-        GNUNET_free (curr_name);
-        if (GNUNET_SYSERR == ret)
-          return GNUNET_SYSERR;
-        if (GNUNET_OK != ret)
-          had_null = GNUNET_YES;
-        break;
-      }
-    case TALER_PQ_RF_RSA_PUBLIC_KEY:
-      {
-        struct GNUNET_CRYPTO_rsa_PublicKey **pk = spec->dst;
-        size_t len;
-        const char *res;
-        int fnum;
-
-	*pk = NULL;
-        fnum = PQfnumber (result,
-                          spec->fname);
-        if (fnum < 0)
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Field `%s' does not exist in result\n",
-                      spec->fname);
-          return GNUNET_SYSERR;
-        }
-        if (PQgetisnull (result,
-                         row,
-                         fnum))
-        {
-          had_null = GNUNET_YES;
-          continue;
-        }
-
-        /* if a field is null, continue but
-         * remember that we now return a different result */
-        len = PQgetlength (result,
-                           row,
-                           fnum);
-        res = PQgetvalue (result,
-                          row,
-                          fnum);
-        *pk = GNUNET_CRYPTO_rsa_public_key_decode (res,
-                                                   len);
-        if (NULL == *pk)
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Field `%s' contains bogus value (fails to decode)\n",
-                      spec->fname);
-          return GNUNET_SYSERR;
-        }
-        break;
-      }
-    case TALER_PQ_RF_RSA_SIGNATURE:
-      {
-        struct GNUNET_CRYPTO_rsa_Signature **sig = spec->dst;
-        size_t len;
-        const char *res;
-        int fnum;
-
-	*sig = NULL;
-        fnum = PQfnumber (result,
-                          spec->fname);
-        if (fnum < 0)
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Field `%s' does not exist in result\n",
-                      spec->fname);
-          return GNUNET_SYSERR;
-        }
-        if (PQgetisnull (result,
-                         row,
-                         fnum))
-        {
-          had_null = GNUNET_YES;
-          continue;
-        }
-
-        /* if a field is null, continue but
-         * remember that we now return a different result */
-        len = PQgetlength (result,
-                           row,
-                           fnum);
-        res = PQgetvalue (result,
-                          row,
-                          fnum);
-        *sig = GNUNET_CRYPTO_rsa_signature_decode (res,
-                                                   len);
-        if (NULL == *sig)
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Field `%s' contains bogus value (fails to decode)\n",
-                      spec->fname);
-          return GNUNET_SYSERR;
-        }
-        break;
-      }
-    case TALER_PQ_RF_TIME_ABSOLUTE:
-      {
-        struct GNUNET_TIME_Absolute *dst = spec->dst;
-	const struct GNUNET_TIME_AbsoluteNBO *res;
-	int fnum;
-
-        fnum = PQfnumber (result,
-                          spec->fname);
-        if (fnum < 0)
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Field `%s' does not exist in result\n",
-                      spec->fname);
-          return GNUNET_SYSERR;
-        }
-        if (PQgetisnull (result,
-                         row,
-                         fnum))
-        {
-          had_null = GNUNET_YES;
-          continue;
-        }
-        GNUNET_assert (NULL != dst);
-        GNUNET_assert (sizeof (struct GNUNET_TIME_AbsoluteNBO) ==
-                       spec->dst_size);
-        res = (const struct GNUNET_TIME_AbsoluteNBO *)
-	  PQgetvalue (result,
-		      row,
-		      fnum);
-	*dst = GNUNET_TIME_absolute_ntoh (*res);
-        break;
-      }
-    case TALER_PQ_RF_UINT16:
-      {
-        uint16_t *dst = spec->dst;
-	const uint16_t *res;
-	int fnum;
-
-        fnum = PQfnumber (result,
-                          spec->fname);
-        if (fnum < 0)
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Field `%s' does not exist in result\n",
-                      spec->fname);
-          return GNUNET_SYSERR;
-        }
-        if (PQgetisnull (result,
-                         row,
-                         fnum))
-        {
-          had_null = GNUNET_YES;
-          continue;
-        }
-        GNUNET_assert (NULL != dst);
-        GNUNET_assert (sizeof (uint16_t) ==
-                       spec->dst_size);
-        res = (uint16_t *) PQgetvalue (result,
-                                       row,
-                                       fnum);
-	*dst = ntohs (*res);
-        break;
-      }
-    case TALER_PQ_RF_UINT32:
-      {
-        uint32_t *dst = spec->dst;
-	const uint32_t *res;
-	int fnum;
-
-        fnum = PQfnumber (result,
-                          spec->fname);
-        if (fnum < 0)
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Field `%s' does not exist in result\n",
-                      spec->fname);
-          return GNUNET_SYSERR;
-        }
-        if (PQgetisnull (result,
-                         row,
-                         fnum))
-        {
-          had_null = GNUNET_YES;
-          continue;
-        }
-        GNUNET_assert (NULL != dst);
-        GNUNET_assert (sizeof (uint32_t) ==
-                       spec->dst_size);
-        res = (uint32_t *) PQgetvalue (result,
-                                       row,
-                                       fnum);
-	*dst = ntohl (*res);
-        break;
-      }
-    case TALER_PQ_RF_UINT64:
-      {
-        uint64_t *dst = spec->dst;
-	const uint64_t *res;
-	int fnum;
-
-        fnum = PQfnumber (result,
-                          spec->fname);
-        if (fnum < 0)
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Field `%s' does not exist in result\n",
-                      spec->fname);
-          return GNUNET_SYSERR;
-        }
-        if (PQgetisnull (result,
-                         row,
-                         fnum))
-        {
-          had_null = GNUNET_YES;
-          continue;
-        }
-        GNUNET_assert (NULL != dst);
-        GNUNET_assert (sizeof (uint64_t) ==
-                       spec->dst_size);
-        res = (uint64_t *) PQgetvalue (result,
-                                       row,
-                                       fnum);
-	*dst = GNUNET_ntohll (*res);
-        break;
-      }
-    case TALER_PQ_RF_JSON:
-      {
-        json_t **dst = spec->dst;
-        char *res;
-	int fnum;
-        json_error_t json_error;
-        size_t slen;
-
-        fnum = PQfnumber (result,
-                          spec->fname);
-        if (fnum < 0)
-        {
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Field `%s' does not exist in result\n",
-                      spec->fname);
-          return GNUNET_SYSERR;
-        }
-        if (PQgetisnull (result,
-                         row,
-                         fnum))
-        {
-          had_null = GNUNET_YES;
-          continue;
-        }
-        GNUNET_assert (NULL != dst);
-        GNUNET_break (0 == spec->dst_size);
-        slen = PQgetlength (result,
-                            row,
-                            fnum);
-        res = (char *) PQgetvalue (result,
-                                   row,
-                                   fnum);
-	*dst = json_loadb (res,
-                           slen,
-                           JSON_REJECT_DUPLICATES,
-                           &json_error);
-        if (NULL == *dst)
-        {
-          TALER_json_warn (json_error);
-          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                      "Failed to parse JSON result for field `%s'\n",
-                      spec->fname);
-          return GNUNET_SYSERR;
-        }
-        break;
-      }
-    default:
-      GNUNET_assert (0);
-      break;
-    }
-  }
-  if (GNUNET_YES == had_null)
-    return GNUNET_NO;
-  return GNUNET_YES;
-}
-
-
-/**
- * Extract a currency amount from a query result according to the
- * given specification.
- *
- * @param result the result to extract the amount from
- * @param row which row of the result to extract the amount from (needed as results can have multiple rows)
- * @param val_name name of the column with the amount's "value", must include the substring "_val".
- * @param frac_name name of the column with the amount's "fractional" value, must include the substring "_frac".
- * @param curr_name name of the column with the amount's currency name, must include the substring "_curr".
- * @param[out] r_amount_nbo where to store the amount, in network byte order
- * @return
- *   #GNUNET_YES if all results could be extracted
- *   #GNUNET_NO if at least one result was NULL
- *   #GNUNET_SYSERR if a result was invalid (non-existing field)
- */
-int
-TALER_PQ_extract_amount_nbo (PGresult *result,
-                             int row,
-                             const char *val_name,
-                             const char *frac_name,
-                             const char *curr_name,
-                             struct TALER_AmountNBO *r_amount_nbo)
-{
-  int val_num;
-  int frac_num;
-  int curr_num;
-  int len;
-
-  /* These checks are simply to check that clients obey by our naming
-     conventions, and not for any functional reason */
-  GNUNET_assert (NULL !=
-                 strstr (val_name,
-                         "_val"));
-  GNUNET_assert (NULL !=
-                 strstr (frac_name,
-                         "_frac"));
-  GNUNET_assert (NULL !=
-                 strstr (curr_name,
-                         "_curr"));
-  /* Set return value to invalid in case we don't finish */
-  memset (r_amount_nbo,
-          0,
-          sizeof (struct TALER_AmountNBO));
-  val_num = PQfnumber (result,
-                       val_name);
-  frac_num = PQfnumber (result,
-                        frac_name);
-  curr_num = PQfnumber (result,
-                        curr_name);
-  if ( (val_num < 0) ||
-       (frac_num < 0) ||
-       (curr_num < 0) )
-  {
-    GNUNET_break (0);
-    return GNUNET_SYSERR;
-  }
-  if ( (PQgetisnull (result,
-                     row,
-                     val_num)) ||
-       (PQgetisnull (result,
-                     row,
-                     frac_num)) ||
-       (PQgetisnull (result,
-                     row,
-                     curr_num)) )
-  {
-    GNUNET_break (0);
-    return GNUNET_NO;
-  }
-  /* Note that Postgres stores value in NBO internally,
-     so no conversion needed in this case */
-  r_amount_nbo->value = *(uint64_t *) PQgetvalue (result,
-                                                  row,
-                                                  val_num);
-  r_amount_nbo->fraction = *(uint32_t *) PQgetvalue (result,
-                                                     row,
-                                                     frac_num);
-  len = GNUNET_MIN (TALER_CURRENCY_LEN - 1,
-                    PQgetlength (result,
-                                 row,
-                                 curr_num));
-  memcpy (r_amount_nbo->currency,
-          PQgetvalue (result,
-                      row,
-                      curr_num),
-          len);
-  return GNUNET_OK;
-}
-
-
-/**
- * Extract a currency amount from a query result according to the
- * given specification.
- *
- * @param result the result to extract the amount from
- * @param row which row of the result to extract the amount from (needed as
- *          results can have multiple rows)
- * @param val_name name of the column with the amount's "value", must include
- *          the substring "_val".
- * @param frac_name name of the column with the amount's "fractional" value,
- *          must include the substring "_frac".
- * @param curr_name name of the column with the amount's currency name, must
- *          include the substring "_curr".
- * @param[out] r_amount where to store the amount, in host byte order
- * @return
- *   #GNUNET_YES if all results could be extracted
- *   #GNUNET_NO if at least one result was NULL
- *   #GNUNET_SYSERR if a result was invalid (non-existing field)
- */
-int
-TALER_PQ_extract_amount (PGresult *result,
-                         int row,
-                         const char *val_name,
-                         const char *frac_name,
-                         const char *curr_name,
-                         struct TALER_Amount *r_amount)
-{
-  struct TALER_AmountNBO amount_nbo;
-  int ret;
-
-  ret = TALER_PQ_extract_amount_nbo (result,
-                                     row,
-                                     val_name,
-                                     frac_name,
-                                     curr_name,
-                                     &amount_nbo);
-  TALER_amount_ntoh (r_amount,
-                     &amount_nbo);
-  return ret;
-}
-
-
-/* end of pq/db_pq.c */
diff --git a/src/pq/pq_helper.c b/src/pq/pq_helper.c
deleted file mode 100644
index d245ffdb8..000000000
--- a/src/pq/pq_helper.c
+++ /dev/null
@@ -1,370 +0,0 @@
-/*
-  This file is part of TALER
-  Copyright (C) 2014, 2015 GNUnet e.V.
-
-  TALER is free software; you can redistribute it and/or modify it under the
-  terms of the GNU General Public License as published by the Free Software
-  Foundation; either version 3, or (at your option) any later version.
-
-  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
-  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
-
-  You should have received a copy of the GNU General Public License along with
-  TALER; see the file COPYING.  If not, If not, see <http://www.gnu.org/licenses/>
-*/
-/**
- * @file pq/pq_helper.c
- * @brief functions to initialize parameter arrays
- * @author Christian Grothoff
- */
-#include "platform.h"
-#include <gnunet/gnunet_util_lib.h>
-#include "taler_pq_lib.h"
-
-
-/**
- * Generate query parameter for a currency, consisting of the three
- * components "value", "fraction" and "currency" in this order. The
- * types must be a 64-bit integer, 32-bit integer and a
- * #TALER_CURRENCY_LEN-sized BLOB/VARCHAR respectively.
- *
- * @param x pointer to the query parameter to pass
- * @return array entry for the query parameters to use
- */
-struct TALER_PQ_QueryParam
-TALER_PQ_query_param_amount_nbo (const struct TALER_AmountNBO *x)
-{
-  struct TALER_PQ_QueryParam res =
-    { TALER_PQ_QF_AMOUNT_NBO, x, sizeof (*x) };
-  return res;
-}
-
-
-/**
- * Generate query parameter for a currency, consisting of the three
- * components "value", "fraction" and "currency" in this order. The
- * types must be a 64-bit integer, 32-bit integer and a
- * #TALER_CURRENCY_LEN-sized BLOB/VARCHAR respectively.
- *
- * @param x pointer to the query parameter to pass
- * @return array entry for the query parameters to use
- */
-struct TALER_PQ_QueryParam
-TALER_PQ_query_param_amount (const struct TALER_Amount *x)
-{
-  struct TALER_PQ_QueryParam res =
-    { TALER_PQ_QF_AMOUNT, x, sizeof (*x) };
-  return res;
-}
-
-
-/**
- * Generate query parameter for an RSA public key.  The
- * database must contain a BLOB type in the respective position.
- *
- * @param x the query parameter to pass
- * @return array entry for the query parameters to use
- */
-struct TALER_PQ_QueryParam
-TALER_PQ_query_param_rsa_public_key (const struct GNUNET_CRYPTO_rsa_PublicKey *x)
-{
-  struct TALER_PQ_QueryParam res =
-    { TALER_PQ_QF_RSA_PUBLIC_KEY, (x), 0 };
-  return res;
-}
-
-
-/**
- * Generate query parameter for an RSA signature.  The
- * database must contain a BLOB type in the respective position.
- *
- * @param x the query parameter to pass
- * @return array entry for the query parameters to use
- */
-struct TALER_PQ_QueryParam
-TALER_PQ_query_param_rsa_signature (const struct GNUNET_CRYPTO_rsa_Signature *x)
-{
-  struct TALER_PQ_QueryParam res =
-    { TALER_PQ_QF_RSA_SIGNATURE, (x), 0 };
-  return res;
-}
-
-
-/**
- * Generate query parameter for an absolute time value.
- * The database must store a 64-bit integer.
- *
- * @param x pointer to the query parameter to pass
- * @return array entry for the query parameters to use
- */
-struct TALER_PQ_QueryParam
-TALER_PQ_query_param_absolute_time (const struct GNUNET_TIME_Absolute *x)
-{
-  struct TALER_PQ_QueryParam res =
-    { TALER_PQ_QF_TIME_ABSOLUTE, x, sizeof (*x) };
-  return res;
-}
-
-
-/**
- * Generate query parameter for an absolute time value.
- * The database must store a 64-bit integer.
- *
- * @param x pointer to the query parameter to pass
- */
-struct TALER_PQ_QueryParam
-TALER_PQ_query_param_absolute_time_nbo(const struct GNUNET_TIME_AbsoluteNBO *x)
-{
-  struct TALER_PQ_QueryParam res =
-    TALER_PQ_query_param_auto_from_type (&x->abs_value_us__);
-  return res;
-}
-
-
-/**
- * Generate query parameter for an uint16_t in host byte order.
- *
- * @param x pointer to the query parameter to pass
- */
-struct TALER_PQ_QueryParam
-TALER_PQ_query_param_uint16 (const uint16_t *x)
-{
-  struct TALER_PQ_QueryParam res =
-    { TALER_PQ_QF_UINT16, x, sizeof (*x) };
-  return res;
-}
-
-
-/**
- * Generate query parameter for an uint32_t in host byte order.
- *
- * @param x pointer to the query parameter to pass
- */
-struct TALER_PQ_QueryParam
-TALER_PQ_query_param_uint32 (const uint32_t *x)
-{
-  struct TALER_PQ_QueryParam res =
-    { TALER_PQ_QF_UINT32, x, sizeof (*x) };
-  return res;
-}
-
-
-/**
- * Generate query parameter for an uint16_t in host byte order.
- *
- * @param x pointer to the query parameter to pass
- */
-struct TALER_PQ_QueryParam
-TALER_PQ_query_param_uint64 (const uint64_t *x)
-{
-  struct TALER_PQ_QueryParam res =
-    { TALER_PQ_QF_UINT64, x, sizeof (*x) };
-  return res;
-}
-
-
-/**
- * Generate query parameter for a JSON object (stored as a string
- * in the DB).
- *
- * @param x pointer to the json object to pass
- */
-struct TALER_PQ_QueryParam
-TALER_PQ_query_param_json (const json_t *x)
-{
-  struct TALER_PQ_QueryParam res =
-    { TALER_PQ_QF_JSON, x, 0 };
-  return res;
-}
-
-
-/**
- * Variable-size result expected.
- *
- * @param name name of the field in the table
- * @param[out] dst where to store the result, allocated
- * @param[out] sptr where to store the size of @a dst
- * @return array entry for the result specification to use
- */
-struct TALER_PQ_ResultSpec
-TALER_PQ_result_spec_variable_size (const char *name,
-                                    void **dst,
-                                    size_t *sptr)
-{
-  struct TALER_PQ_ResultSpec res =
-    { TALER_PQ_RF_VARSIZE_BLOB, (void *) (dst), 0, name, sptr };
-  return res;
-}
-
-
-/**
- * Currency amount expected.
- *
- * @param name name of the field in the table
- * @param[out] amount where to store the result
- * @return array entry for the result specification to use
- */
-struct TALER_PQ_ResultSpec
-TALER_PQ_result_spec_amount_nbo (const char *name,
-				 struct TALER_AmountNBO *amount)
-{
-  struct TALER_PQ_ResultSpec res =
-    {TALER_PQ_RF_AMOUNT_NBO, (void *) amount, sizeof (*amount), name, NULL };
-  return res;
-}
-
-
-/**
- * Currency amount expected.
- *
- * @param name name of the field in the table
- * @param[out] amount where to store the result
- * @return array entry for the result specification to use
- */
-struct TALER_PQ_ResultSpec
-TALER_PQ_result_spec_amount (const char *name,
-			     struct TALER_Amount *amount)
-{
-  struct TALER_PQ_ResultSpec res =
-    {TALER_PQ_RF_AMOUNT, (void *) amount, sizeof (*amount), name, NULL };
-  return res;
-}
-
-
-/**
- * RSA public key expected.
- *
- * @param name name of the field in the table
- * @param[out] rsa where to store the result
- * @return array entry for the result specification to use
- */
-struct TALER_PQ_ResultSpec
-TALER_PQ_result_spec_rsa_public_key (const char *name,
-				     struct GNUNET_CRYPTO_rsa_PublicKey **rsa)
-{
-  struct TALER_PQ_ResultSpec res =
-    {TALER_PQ_RF_RSA_PUBLIC_KEY, (void *) rsa, 0, name, NULL };
-  return res;
-}
-
-
-/**
- * RSA signature expected.
- *
- * @param name name of the field in the table
- * @param[out] sig where to store the result;
- * @return array entry for the result specification to use
- */
-struct TALER_PQ_ResultSpec
-TALER_PQ_result_spec_rsa_signature (const char *name,
-				    struct GNUNET_CRYPTO_rsa_Signature **sig)
-{
-  struct TALER_PQ_ResultSpec res =
-    {TALER_PQ_RF_RSA_SIGNATURE, (void *) sig, 0, (name), NULL };
-  return res;
-}
-
-
-/**
- * Absolute time expected.
- *
- * @param name name of the field in the table
- * @param[out] at where to store the result
- * @return array entry for the result specification to use
- */
-struct TALER_PQ_ResultSpec
-TALER_PQ_result_spec_absolute_time (const char *name,
-				    struct GNUNET_TIME_Absolute *at)
-{
-  struct TALER_PQ_ResultSpec res =
-    {TALER_PQ_RF_TIME_ABSOLUTE, (void *) at, sizeof (*at), (name), NULL };
-  return res;
-}
-
-
-/**
- * Absolute time expected.
- *
- * @param name name of the field in the table
- * @param[out] at where to store the result
- * @return array entry for the result specification to use
- */
-struct TALER_PQ_ResultSpec
-TALER_PQ_result_spec_absolute_time_nbo (const char *name,
-                                        struct GNUNET_TIME_AbsoluteNBO *at)
-{
-  struct TALER_PQ_ResultSpec res =
-    TALER_PQ_result_spec_auto_from_type(name, &at->abs_value_us__);
-  return res;
-}
-
-
-/**
- * uint16_t expected.
- *
- * @param name name of the field in the table
- * @param[out] u16 where to store the result
- * @return array entry for the result specification to use
- */
-struct TALER_PQ_ResultSpec
-TALER_PQ_result_spec_uint16 (const char *name,
-                             uint16_t *u16)
-{
-  struct TALER_PQ_ResultSpec res =
-    {TALER_PQ_RF_UINT16, (void *) u16, sizeof (*u16), (name), NULL };
-  return res;
-}
-
-
-/**
- * uint32_t expected.
- *
- * @param name name of the field in the table
- * @param[out] u32 where to store the result
- * @return array entry for the result specification to use
- */
-struct TALER_PQ_ResultSpec
-TALER_PQ_result_spec_uint32 (const char *name,
-                             uint32_t *u32)
-{
-  struct TALER_PQ_ResultSpec res =
-    {TALER_PQ_RF_UINT32, (void *) u32, sizeof (*u32), (name), NULL };
-  return res;
-}
-
-
-/**
- * uint64_t expected.
- *
- * @param name name of the field in the table
- * @param[out] u64 where to store the result
- * @return array entry for the result specification to use
- */
-struct TALER_PQ_ResultSpec
-TALER_PQ_result_spec_uint64 (const char *name,
-                             uint64_t *u64)
-{
-  struct TALER_PQ_ResultSpec res =
-    {TALER_PQ_RF_UINT64, (void *) u64, sizeof (*u64), (name), NULL };
-  return res;
-}
-
-
-/**
- * json_t expected.
- *
- * @param name name of the field in the table
- * @param[out] jp where to store the result
- * @return array entry for the result specification to use
- */
-struct TALER_PQ_ResultSpec
-TALER_PQ_result_spec_json (const char *name,
-                           json_t **jp)
-{
-  struct TALER_PQ_ResultSpec res =
-    {TALER_PQ_RF_JSON, (void *) jp, 0, (name), NULL };
-  return res;
-}
-
-/* end of pq_helper.c */
diff --git a/src/pq/pq_query_helper.c b/src/pq/pq_query_helper.c
new file mode 100644
index 000000000..5d2e9ce06
--- /dev/null
+++ b/src/pq/pq_query_helper.c
@@ -0,0 +1,208 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2014, 2015, 2016 GNUnet e.V.
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file pq/pq_query_helper.c
+ * @brief helper functions for Taler-specific libpq (PostGres) interactions
+ * @author Sree Harsha Totakura <sreeharsha@totakura.in>
+ * @author Florian Dold
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <gnunet/gnunet_util_lib.h>
+#include <gnunet/gnunet_pq_lib.h>
+#include "taler_pq_lib.h"
+
+
+/**
+ * Function called to convert input argument into SQL parameters.
+ *
+ * @param cls closure
+ * @param data pointer to input argument, here a `struct TALER_AmountNBO`
+ * @param data_len number of bytes in @a data (if applicable)
+ * @param[out] param_values SQL data to set
+ * @param[out] param_lengths SQL length data to set
+ * @param[out] param_formats SQL format data to set
+ * @param param_length number of entries available in the @a param_values, @a param_lengths and @a param_formats arrays
+ * @param[out] scratch buffer for dynamic allocations (to be done via #GNUNET_malloc()
+ * @param scratch_length number of entries left in @a scratch
+ * @return -1 on error, number of offsets used in @a scratch otherwise
+ */
+static int
+qconv_amount_nbo (void *cls,
+		  const void *data,
+		  size_t data_len,
+		  void *param_values[],
+		  int param_lengths[],
+		  int param_formats[],
+		  unsigned int param_length,
+		  void *scratch[],
+		  unsigned int scratch_length)
+{
+  const struct TALER_AmountNBO *amount = data;
+  unsigned int off = 0;
+
+  GNUNET_assert (3 == param_length);
+  param_values[off] = (void *) &amount->value;
+  param_lengths[off] = sizeof (amount->value);
+  param_formats[off] = 1;
+  off++;
+  param_values[off] = (void *) &amount->fraction;
+  param_lengths[off] = sizeof (amount->fraction);
+  param_formats[off] = 1;
+  off++;
+  param_values[off] = (void *) amount->currency;
+  param_lengths[off] = strlen (amount->currency);
+  param_formats[off] = 1;
+  return 0;
+}
+
+
+/**
+ * Generate query parameter for a currency, consisting of the three
+ * components "value", "fraction" and "currency" in this order. The
+ * types must be a 64-bit integer, 32-bit integer and a
+ * #TALER_CURRENCY_LEN-sized BLOB/VARCHAR respectively.
+ *
+ * @param x pointer to the query parameter to pass
+ * @return array entry for the query parameters to use
+ */
+struct GNUNET_PQ_QueryParam
+TALER_PQ_query_param_amount_nbo (const struct TALER_AmountNBO *x)
+{
+  struct GNUNET_PQ_QueryParam res =
+    { &qconv_amount_nbo, NULL, x, sizeof (*x), 3 };
+  return res;
+}
+
+
+/**
+ * Function called to convert input argument into SQL parameters.
+ *
+ * @param cls closure
+ * @param data pointer to input argument, here a `struct TALER_Amount`
+ * @param data_len number of bytes in @a data (if applicable)
+ * @param[out] param_values SQL data to set
+ * @param[out] param_lengths SQL length data to set
+ * @param[out] param_formats SQL format data to set
+ * @param param_length number of entries available in the @a param_values, @a param_lengths and @a param_formats arrays
+ * @param[out] scratch buffer for dynamic allocations (to be done via #GNUNET_malloc()
+ * @param scratch_length number of entries left in @a scratch
+ * @return -1 on error, number of offsets used in @a scratch otherwise
+ */
+static int
+qconv_amount (void *cls,
+	      const void *data,
+	      size_t data_len,
+	      void *param_values[],
+	      int param_lengths[],
+	      int param_formats[],
+	      unsigned int param_length,
+	      void *scratch[],
+	      unsigned int scratch_length)
+{
+  const struct TALER_Amount *amount_hbo = data;
+  struct TALER_AmountNBO *amount;
+
+  amount = GNUNET_new (struct TALER_AmountNBO);
+  scratch[0] = amount;
+  TALER_amount_hton (amount,
+		     amount_hbo);
+  qconv_amount_nbo (cls,
+		    amount,
+		    sizeof (struct TALER_AmountNBO),
+		    param_values,
+		    param_lengths,
+		    param_formats,
+		    param_length,
+		    &scratch[1],
+		    scratch_length - 1);
+  return 1;
+}
+
+
+/**
+ * Generate query parameter for a currency, consisting of the three
+ * components "value", "fraction" and "currency" in this order. The
+ * types must be a 64-bit integer, 32-bit integer and a
+ * #TALER_CURRENCY_LEN-sized BLOB/VARCHAR respectively.
+ *
+ * @param x pointer to the query parameter to pass
+ * @return array entry for the query parameters to use
+ */
+struct GNUNET_PQ_QueryParam
+TALER_PQ_query_param_amount (const struct TALER_Amount *x)
+{
+  struct GNUNET_PQ_QueryParam res =
+    { &qconv_amount, NULL, x, sizeof (*x), 3 };
+  return res;
+}
+
+
+/**
+ * Function called to convert input argument into SQL parameters.
+ *
+ * @param cls closure
+ * @param data pointer to input argument, here a `json_t *`
+ * @param data_len number of bytes in @a data (if applicable)
+ * @param[out] param_values SQL data to set
+ * @param[out] param_lengths SQL length data to set
+ * @param[out] param_formats SQL format data to set
+ * @param param_length number of entries available in the @a param_values, @a param_lengths and @a param_formats arrays
+ * @param[out] scratch buffer for dynamic allocations (to be done via #GNUNET_malloc()
+ * @param scratch_length number of entries left in @a scratch
+ * @return -1 on error, number of offsets used in @a scratch otherwise
+ */
+static int
+qconv_json (void *cls,
+	    const void *data,
+	    size_t data_len,
+	    void *param_values[],
+	    int param_lengths[],
+	    int param_formats[],
+	    unsigned int param_length,
+	    void *scratch[],
+	    unsigned int scratch_length)
+{
+  const json_t *json = data;
+  char *str;
+  
+  str = json_dumps (json, JSON_COMPACT);
+  if (NULL == str)
+    return -1;
+  scratch[0] = str;
+  param_values[0] = (void *) str;
+  param_lengths[0] = strlen (str);
+  param_formats[0] = 1;
+  return 1;
+}
+
+
+/**
+ * Generate query parameter for a JSON object (stored as a string
+ * in the DB).
+ *
+ * @param x pointer to the json object to pass
+ */
+struct GNUNET_PQ_QueryParam
+TALER_PQ_query_param_json (const json_t *x)
+{
+  struct GNUNET_PQ_QueryParam res =
+    { &qconv_json, NULL, x, 0, 1 };
+  return res;
+}
+
+
+/* end of pq/pq_query_helper.c */
diff --git a/src/pq/pq_result_helper.c b/src/pq/pq_result_helper.c
new file mode 100644
index 000000000..c8b3b01fc
--- /dev/null
+++ b/src/pq/pq_result_helper.c
@@ -0,0 +1,358 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2014, 2015, 2016 GNUnet e.V.
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file pq/pq_result_helper.c
+ * @brief functions to initialize parameter arrays
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <gnunet/gnunet_util_lib.h>
+#include "taler_pq_lib.h"
+
+
+/**
+ * Extract a currency amount from a query result according to the
+ * given specification.
+ *
+ * @param result the result to extract the amount from
+ * @param row which row of the result to extract the amount from (needed as results can have multiple rows)
+ * @param val_name name of the column with the amount's "value", must include the substring "_val".
+ * @param frac_name name of the column with the amount's "fractional" value, must include the substring "_frac".
+ * @param curr_name name of the column with the amount's currency name, must include the substring "_curr".
+ * @param[out] r_amount_nbo where to store the amount, in network byte order
+ * @return
+ *   #GNUNET_YES if all results could be extracted
+ *   #GNUNET_NO if at least one result was NULL
+ *   #GNUNET_SYSERR if a result was invalid (non-existing field)
+ */
+static int
+extract_amount_nbo_helper (PGresult *result,
+			   int row,
+			   const char *val_name,
+			   const char *frac_name,
+			   const char *curr_name,
+			   struct TALER_AmountNBO *r_amount_nbo)
+{
+  int val_num;
+  int frac_num;
+  int curr_num;
+  int len;
+
+  /* These checks are simply to check that clients obey by our naming
+     conventions, and not for any functional reason */
+  GNUNET_assert (NULL !=
+                 strstr (val_name,
+                         "_val"));
+  GNUNET_assert (NULL !=
+                 strstr (frac_name,
+                         "_frac"));
+  GNUNET_assert (NULL !=
+                 strstr (curr_name,
+                         "_curr"));
+  /* Set return value to invalid in case we don't finish */
+  memset (r_amount_nbo,
+          0,
+          sizeof (struct TALER_AmountNBO));
+  val_num = PQfnumber (result,
+                       val_name);
+  frac_num = PQfnumber (result,
+                        frac_name);
+  curr_num = PQfnumber (result,
+                        curr_name);
+  if ( (val_num < 0) ||
+       (frac_num < 0) ||
+       (curr_num < 0) )
+  {
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  if ( (PQgetisnull (result,
+                     row,
+                     val_num)) ||
+       (PQgetisnull (result,
+                     row,
+                     frac_num)) ||
+       (PQgetisnull (result,
+                     row,
+                     curr_num)) )
+  {
+    GNUNET_break (0);
+    return GNUNET_NO;
+  }
+  /* Note that Postgres stores value in NBO internally,
+     so no conversion needed in this case */
+  r_amount_nbo->value = *(uint64_t *) PQgetvalue (result,
+                                                  row,
+                                                  val_num);
+  r_amount_nbo->fraction = *(uint32_t *) PQgetvalue (result,
+                                                     row,
+                                                     frac_num);
+  len = GNUNET_MIN (TALER_CURRENCY_LEN - 1,
+                    PQgetlength (result,
+                                 row,
+                                 curr_num));
+  memcpy (r_amount_nbo->currency,
+          PQgetvalue (result,
+                      row,
+                      curr_num),
+          len);
+  return GNUNET_OK;
+}
+
+
+/**
+ * Extract data from a Postgres database @a result at row @a row.
+ *
+ * @param cls closure
+ * @param result where to extract data from
+ * @param int row to extract data from
+ * @param fname name (or prefix) of the fields to extract from
+ * @param[in,out] dst_size where to store size of result, may be NULL
+ * @param[out] dst where to store the result
+ * @return
+ *   #GNUNET_YES if all results could be extracted
+ *   #GNUNET_NO if at least one result was NULL
+ *   #GNUNET_SYSERR if a result was invalid (non-existing field)
+ */ 
+static int
+extract_amount_nbo (void *cls,
+		    PGresult *result,
+		    int row,
+		    const char *fname,
+		    size_t *dst_size,
+		    void *dst)
+{
+  char *val_name;
+  char *frac_name;
+  char *curr_name;
+  int ret;
+  
+  GNUNET_asprintf (&val_name,
+		   "%s_val",
+		   fname);
+  GNUNET_asprintf (&frac_name,
+		   "%s_frac",
+		   fname);
+  GNUNET_asprintf (&curr_name,
+		   "%s_curr",
+		   fname);
+  ret = extract_amount_nbo_helper (result,
+				   row,
+				   val_name,
+				   frac_name,
+				   curr_name,
+				   dst);
+  GNUNET_free (val_name);
+  GNUNET_free (frac_name);
+  GNUNET_free (curr_name);
+  return ret;
+}
+
+
+/**
+ * Currency amount expected.
+ *
+ * @param name name of the field in the table
+ * @param[out] amount where to store the result
+ * @return array entry for the result specification to use
+ */
+struct GNUNET_PQ_ResultSpec
+TALER_PQ_result_spec_amount_nbo (const char *name,
+				 struct TALER_AmountNBO *amount)
+{
+  struct GNUNET_PQ_ResultSpec res =
+    { &extract_amount_nbo, NULL, NULL,
+      (void *) amount, sizeof (*amount), 
+      name, NULL };
+  return res;
+}
+
+
+/**
+ * Extract data from a Postgres database @a result at row @a row.
+ *
+ * @param cls closure
+ * @param result where to extract data from
+ * @param int row to extract data from
+ * @param fname name (or prefix) of the fields to extract from
+ * @param[in,out] dst_size where to store size of result, may be NULL
+ * @param[out] dst where to store the result
+ * @return
+ *   #GNUNET_YES if all results could be extracted
+ *   #GNUNET_NO if at least one result was NULL
+ *   #GNUNET_SYSERR if a result was invalid (non-existing field)
+ */ 
+static int
+extract_amount (void *cls,
+		PGresult *result,
+		int row,
+		const char *fname,
+		size_t *dst_size,
+		void *dst)
+{
+  struct TALER_Amount *r_amount = dst;
+  char *val_name;
+  char *frac_name;
+  char *curr_name;
+  struct TALER_AmountNBO amount_nbo;
+  int ret;
+  
+  GNUNET_asprintf (&val_name,
+		   "%s_val",
+		   fname);
+  GNUNET_asprintf (&frac_name,
+		   "%s_frac",
+		   fname);
+  GNUNET_asprintf (&curr_name,
+		   "%s_curr",
+		   fname);
+  ret = extract_amount_nbo_helper (result,
+				   row,
+				   val_name,
+				   frac_name,
+				   curr_name,
+				   &amount_nbo);
+  TALER_amount_ntoh (r_amount,
+                     &amount_nbo);
+  GNUNET_free (val_name);
+  GNUNET_free (frac_name);
+  GNUNET_free (curr_name);
+  return ret;
+}
+
+
+/**
+ * Currency amount expected.
+ *
+ * @param name name of the field in the table
+ * @param[out] amount where to store the result
+ * @return array entry for the result specification to use
+ */
+struct GNUNET_PQ_ResultSpec
+TALER_PQ_result_spec_amount (const char *name,
+			     struct TALER_Amount *amount)
+{
+  struct GNUNET_PQ_ResultSpec res =
+    { &extract_amount, NULL, NULL,
+      (void *) amount, sizeof (*amount),
+      name, NULL };
+  return res;
+}
+
+
+/**
+ * Extract data from a Postgres database @a result at row @a row.
+ *
+ * @param cls closure
+ * @param result where to extract data from
+ * @param int row to extract data from
+ * @param fname name (or prefix) of the fields to extract from
+ * @param[in,out] dst_size where to store size of result, may be NULL
+ * @param[out] dst where to store the result
+ * @return
+ *   #GNUNET_YES if all results could be extracted
+ *   #GNUNET_NO if at least one result was NULL
+ *   #GNUNET_SYSERR if a result was invalid (non-existing field)
+ */ 
+static int
+extract_json (void *cls,
+	      PGresult *result,
+	      int row,
+	      const char *fname,
+	      size_t *dst_size,
+	      void *dst)
+{
+  json_t **j_dst = dst;
+  const char *res;
+  int fnum;
+  json_error_t json_error;
+  size_t slen;
+  
+  fnum = PQfnumber (result,
+		    fname);
+  if (fnum < 0)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+		"Field `%s' does not exist in result\n",
+		fname);
+    return GNUNET_SYSERR;
+  }
+  if (PQgetisnull (result,
+		   row,
+		   fnum))
+    return GNUNET_NO;
+  slen = PQgetlength (result,
+		      row,
+		      fnum);
+  res = (const char *) PQgetvalue (result,
+				   row,
+				   fnum);
+  *j_dst = json_loadb (res,
+		       slen,
+		       JSON_REJECT_DUPLICATES,
+		       &json_error);
+  if (NULL == *j_dst)
+  {
+    TALER_json_warn (json_error);
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+		"Failed to parse JSON result for field `%s'\n",
+		fname);
+    return GNUNET_SYSERR;
+  }
+  return GNUNET_OK;
+}
+
+
+/**
+ * Function called to clean up memory allocated
+ * by a #GNUNET_PQ_ResultConverter.
+ *
+ * @param cls closure
+ * @param rd result data to clean up
+ */
+static void
+clean_json (void *cls,
+	    void *rd)
+{
+  json_t **dst = rd;
+
+  if (NULL != *dst)
+  {
+    json_decref (*dst);
+    *dst = NULL;
+  }
+}
+
+
+/**
+ * json_t expected.
+ *
+ * @param name name of the field in the table
+ * @param[out] jp where to store the result
+ * @return array entry for the result specification to use
+ */
+struct GNUNET_PQ_ResultSpec
+TALER_PQ_result_spec_json (const char *name,
+                           json_t **jp)
+{
+  struct GNUNET_PQ_ResultSpec res =
+    { &extract_json, &clean_json, NULL,
+      (void *) jp, 0, 
+      name, NULL };
+  return res;
+}
+
+/* end of pq_result_helper.c */
diff --git a/src/pq/test_pq.c b/src/pq/test_pq.c
index f0413d1ff..95cfb715d 100644
--- a/src/pq/test_pq.c
+++ b/src/pq/test_pq.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  (C) 2015 GNUnet e.V.
+  (C) 2015, 2016 GNUnet e.V.
 
   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU General Public License as published by the Free Software
@@ -48,47 +48,27 @@ postgres_prepare (PGconn *db_conn)
 
   PREPARE ("test_insert",
            "INSERT INTO test_pq ("
-           " pub"
-           ",sig"
-           ",abs_time"
-           ",forever"
-           ",hash"
-           ",hamount_val"
+           " hamount_val"
            ",hamount_frac"
            ",hamount_curr"
            ",namount_val"
            ",namount_frac"
            ",namount_curr"
-           ",vsize"
-           ",u16"
-           ",u32"
-           ",u64"
            ",json"
            ") VALUES "
            "($1, $2, $3, $4, $5, $6,"
-            "$7, $8, $9, $10, $11, $12, $13, $14, $15, $16);",
-           16, NULL);
+            "$7);",
+           7, NULL);
   PREPARE ("test_select",
            "SELECT"
-           " pub"
-           ",sig"
-           ",abs_time"
-           ",forever"
-           ",hash"
-           ",hamount_val"
+           " hamount_val"
            ",hamount_frac"
            ",hamount_curr"
            ",namount_val"
            ",namount_frac"
            ",namount_curr"
-	   ",vsize"
-           ",u16"
-           ",u32"
-           ",u64"
            ",json"
-           " FROM test_pq"
-           " ORDER BY abs_time DESC "
-           " LIMIT 1;",
+           " FROM test_pq;",
            0, NULL);
   return GNUNET_OK;
 #undef PREPARE
@@ -103,40 +83,15 @@ postgres_prepare (PGconn *db_conn)
 static int
 run_queries (PGconn *conn)
 {
-  struct GNUNET_CRYPTO_rsa_PublicKey *pub;
-  struct GNUNET_CRYPTO_rsa_PublicKey *pub2 = NULL;
-  struct GNUNET_CRYPTO_rsa_Signature *sig;
-  struct GNUNET_CRYPTO_rsa_Signature *sig2 = NULL;
-  struct GNUNET_TIME_Absolute abs_time = GNUNET_TIME_absolute_get ();
-  struct GNUNET_TIME_Absolute abs_time2;
-  struct GNUNET_TIME_Absolute forever = GNUNET_TIME_UNIT_FOREVER_ABS;
-  struct GNUNET_TIME_Absolute forever2;
-  struct GNUNET_HashCode hc;
-  struct GNUNET_HashCode hc2;
   struct TALER_Amount hamount;
   struct TALER_Amount hamount2;
   struct TALER_AmountNBO namount;
   struct TALER_AmountNBO namount2;
   PGresult *result;
   int ret;
-  struct GNUNET_CRYPTO_rsa_PrivateKey *priv;
-  char msg[] = "Hello";
-  void *msg2;
-  size_t msg2_len;
-  uint16_t u16;
-  uint16_t u162;
-  uint32_t u32;
-  uint32_t u322;
-  uint64_t u64;
-  uint64_t u642;
   json_t *json;
   json_t *json2;
 
-  priv = GNUNET_CRYPTO_rsa_private_key_create (1024);
-  pub = GNUNET_CRYPTO_rsa_private_key_get_public (priv);
-  sig = GNUNET_CRYPTO_rsa_sign (priv,
-				msg,
-				sizeof (msg));
   GNUNET_assert (GNUNET_OK ==
                  TALER_string_to_amount ("EUR:5.5",
                                          &hamount));
@@ -145,87 +100,53 @@ run_queries (PGconn *conn)
   GNUNET_assert (GNUNET_OK ==
                  TALER_string_to_amount ("EUR:4.4",
                                          &hamount));
-  u16 = 16;
-  u32 = 32;
-  u64 = 64;
   json = json_object ();
   json_object_set (json, "foo", json_integer (42));
   GNUNET_assert (NULL != json);
-  /* FIXME: test TALER_PQ_result_spec_variable_size */
+  /* FIXME: test GNUNET_PQ_result_spec_variable_size */
   {
-    struct TALER_PQ_QueryParam params_insert[] = {
-      TALER_PQ_query_param_rsa_public_key (pub),
-      TALER_PQ_query_param_rsa_signature (sig),
-      TALER_PQ_query_param_absolute_time (&abs_time),
-      TALER_PQ_query_param_absolute_time (&forever),
-      TALER_PQ_query_param_auto_from_type (&hc),
+    struct GNUNET_PQ_QueryParam params_insert[] = {
       TALER_PQ_query_param_amount (&hamount),
       TALER_PQ_query_param_amount_nbo (&namount),
-      TALER_PQ_query_param_fixed_size (msg, strlen (msg)),
-      TALER_PQ_query_param_uint16 (&u16),
-      TALER_PQ_query_param_uint32 (&u32),
-      TALER_PQ_query_param_uint64 (&u64),
       TALER_PQ_query_param_json (json),
-      TALER_PQ_query_param_end
+      GNUNET_PQ_query_param_end
     };
-    struct TALER_PQ_QueryParam params_select[] = {
-      TALER_PQ_query_param_end
+    struct GNUNET_PQ_QueryParam params_select[] = {
+      GNUNET_PQ_query_param_end
     };
-    struct TALER_PQ_ResultSpec results_select[] = {
-      TALER_PQ_result_spec_rsa_public_key ("pub", &pub2),
-      TALER_PQ_result_spec_rsa_signature ("sig", &sig2),
-      TALER_PQ_result_spec_absolute_time ("abs_time", &abs_time2),
-      TALER_PQ_result_spec_absolute_time ("forever", &forever2),
-      TALER_PQ_result_spec_auto_from_type ("hash", &hc2),
+    struct GNUNET_PQ_ResultSpec results_select[] = {
       TALER_PQ_result_spec_amount ("hamount", &hamount2),
       TALER_PQ_result_spec_amount_nbo ("namount", &namount2),
-      TALER_PQ_result_spec_variable_size ("vsize", &msg2, &msg2_len),
-      TALER_PQ_result_spec_uint16 ("u16", &u162),
-      TALER_PQ_result_spec_uint32 ("u32", &u322),
-      TALER_PQ_result_spec_uint64 ("u64", &u642),
       TALER_PQ_result_spec_json ("json", &json2),
-      TALER_PQ_result_spec_end
+      GNUNET_PQ_result_spec_end
     };
 
-    result = TALER_PQ_exec_prepared (conn,
-				     "test_insert",
-				     params_insert);
+    result = GNUNET_PQ_exec_prepared (conn,
+				      "test_insert",
+				      params_insert);
     if (PGRES_COMMAND_OK != PQresultStatus (result))
     {
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
 		  "Database failure: %s\n",
 		  PQresultErrorMessage (result));
       PQclear (result);
-      GNUNET_CRYPTO_rsa_signature_free (sig);
-      GNUNET_CRYPTO_rsa_private_key_free (priv);
-      GNUNET_CRYPTO_rsa_public_key_free (pub);
       return 1;
     }
 
     PQclear (result);
-    result = TALER_PQ_exec_prepared (conn,
-				     "test_select",
-				     params_select);
+    result = GNUNET_PQ_exec_prepared (conn,
+				      "test_select",
+				      params_select);
     if (1 !=
 	PQntuples (result))
     {
       GNUNET_break (0);
       PQclear (result);
-      GNUNET_CRYPTO_rsa_signature_free (sig);
-      GNUNET_CRYPTO_rsa_private_key_free (priv);
-      GNUNET_CRYPTO_rsa_public_key_free (pub);
       return 1;
     }
-    ret = TALER_PQ_extract_result (result,
-				   results_select,
-				   0);
-    GNUNET_break (GNUNET_YES == ret);
-    GNUNET_break (abs_time.abs_value_us == abs_time2.abs_value_us);
-    GNUNET_break (forever.abs_value_us == forever2.abs_value_us);
-    GNUNET_break (0 ==
-		  memcmp (&hc,
-			  &hc2,
-			  sizeof (struct GNUNET_HashCode)));
+    ret = GNUNET_PQ_extract_result (result,
+				    results_select,
+				    0);
     GNUNET_break (0 ==
 		  TALER_amount_cmp (&hamount,
 				    &hamount2));
@@ -237,28 +158,11 @@ run_queries (PGconn *conn)
     GNUNET_break (0 ==
 		  TALER_amount_cmp (&hamount,
 				    &hamount2));
-    GNUNET_break (0 ==
-		  GNUNET_CRYPTO_rsa_signature_cmp (sig,
-						   sig2));
-    GNUNET_break (0 ==
-		  GNUNET_CRYPTO_rsa_public_key_cmp (pub,
-						    pub2));
-    GNUNET_break (strlen (msg) == msg2_len);
-    GNUNET_break (0 ==
-		  strncmp (msg,
-			   msg2,
-			   msg2_len));
-    GNUNET_break (16 == u162);
-    GNUNET_break (32 == u322);
-    GNUNET_break (64 == u642);
     GNUNET_break (42 == json_integer_value (json_object_get (json2, "foo")));
     json_decref (json2);
-    TALER_PQ_cleanup_result (results_select);
+    GNUNET_PQ_cleanup_result (results_select);
     PQclear (result);
   }
-  GNUNET_CRYPTO_rsa_signature_free (sig);
-  GNUNET_CRYPTO_rsa_private_key_free (priv);
-  GNUNET_CRYPTO_rsa_public_key_free (pub);
   if (GNUNET_OK != ret)
     return 1;
 
@@ -290,21 +194,12 @@ main(int argc,
 
   result = PQexec (conn,
 		   "CREATE TEMPORARY TABLE IF NOT EXISTS test_pq ("
-		   " pub BYTEA NOT NULL"
-		   ",sig BYTEA NOT NULL"
-		   ",abs_time INT8 NOT NULL"
-		   ",forever INT8 NOT NULL"
-		   ",hash BYTEA NOT NULL CHECK(LENGTH(hash)=64)"
-		   ",hamount_val INT8 NOT NULL"
+		   " hamount_val INT8 NOT NULL"
 		   ",hamount_frac INT4 NOT NULL"
 		   ",hamount_curr VARCHAR("TALER_CURRENCY_LEN_STR") NOT NULL"
 		   ",namount_val INT8 NOT NULL"
 		   ",namount_frac INT4 NOT NULL"
 		   ",namount_curr VARCHAR("TALER_CURRENCY_LEN_STR") NOT NULL"
-		   ",vsize VARCHAR NOT NULL"
-		   ",u16 INT2 NOT NULL"
-		   ",u32 INT4 NOT NULL"
-		   ",u64 INT8 NOT NULL"
 		   ",json VARCHAR NOT NULL"
 		   ")");
   if (PGRES_COMMAND_OK != PQresultStatus (result))