pg_dump feature patch to allow selection of rows to dump via where - Mailing list pgsql-patches

In order to support some automation, I needed the ability to pull out
subsets of postgres tables in a format which could be loaded into
other postgres databases.  Instead of writing a utility to replicate
the functionality in pg_dump, I created a new flag, --where, which
allows you to postpend where (or order or limit or whatever) sql
fragments at the end of the select done by pg_dump.

You must use the --insert option with this so that it will generate
inserts (which is done via select) instead of copy (which is done via
copy).

You almost certain will need to also use the --table option since most
likely the sql fragment will only be valid for one table instead of
all tables.

I find it very useful and hope you do to.  This patch was created with
7.x postgresql, but if it doesn't apply cleanly against 8.x, I can
probably update it for you.

Index: doc/src/sgml/ref/pg_dump.sgml
===================================================================
RCS file: /src/cvs/postgres/doc/src/sgml/ref/pg_dump.sgml,v
retrieving revision 1.1.1.5
diff -u -u -r1.1.1.5 pg_dump.sgml
--- doc/src/sgml/ref/pg_dump.sgml    21 Oct 2004 22:49:04 -0000    1.1.1.5
+++ doc/src/sgml/ref/pg_dump.sgml    9 Sep 2005 23:31:28 -0000
@@ -412,6 +412,23 @@
      </varlistentry>

      <varlistentry>
+      <term><option>-w <replaceable class="parameter">sql fragment</replaceable></option></term>
+      <term><option>--where <replaceable class="parameter">sql fragment</replaceable></option></term>
+      <listitem>
+       <para>
+         When performing a <option>--table</option> and <option>--insert</option> dump, allow an
+         additional restriction (or other SQL fragment such as ORDER or LIMIT)
+         to be placed on the data being retrieved for output.  Example:
+
+<screen>
+<prompt>$</prompt> <userinput>pg_dump -dt pg_database -w "WHERE datname NOT LIKE 'template%'"</userinput>
+</screen>
+
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>-x</></term>
       <term><option>--no-privileges</></term>
       <term><option>--no-acl</></term>
Index: src/bin/pg_dump/pg_dump.c
===================================================================
RCS file: /src/cvs/postgres/src/bin/pg_dump/pg_dump.c,v
retrieving revision 1.1.1.6
diff -u -u -r1.1.1.6 pg_dump.c
--- src/bin/pg_dump/pg_dump.c    26 May 2004 18:27:23 -0000    1.1.1.6
+++ src/bin/pg_dump/pg_dump.c    9 Sep 2005 22:02:17 -0000
@@ -141,6 +141,7 @@

 static char *selectTableName = NULL;    /* name of a single table to dump */
 static char *selectSchemaName = NULL;    /* name of a single schema to dump */
+static char *selectWhere = NULL;    /* restriction to place on (typically) single table you are dumping */

 char        g_opaque_type[10];    /* name for the opaque type */

@@ -209,6 +210,7 @@
         {"compress", required_argument, NULL, 'Z'},
         {"help", no_argument, NULL, '?'},
         {"version", no_argument, NULL, 'V'},
+        {"where", required_argument, NULL, 'w'},

         /*
          * the following options don't have an equivalent short option
@@ -258,7 +260,7 @@
         }
     }

-    while ((c = getopt_long(argc, argv, "abcCdDf:F:h:in:oOp:RsS:t:uU:vWxX:Z:",
+    while ((c = getopt_long(argc, argv, "abcCdDf:F:h:in:oOp:RsS:t:uU:vw:WxX:Z:",
                             long_options, &optindex)) != -1)
     {
         switch (c)
@@ -352,6 +354,10 @@
                 g_verbose = true;
                 break;

+            case 'w':
+                selectWhere = strdup(optarg);
+                break;
+
             case 'W':
                 force_password = true;
                 break;
@@ -640,6 +646,8 @@
     printf(_("  -S, --superuser=NAME     specify the superuser user name to use in\n"
              "                           plain text format\n"));
     printf(_("  -t, --table=TABLE        dump the named table only\n"));
+    printf(_("  -w, --where='SQLfrag'    If dumping named table and dumping as insert,\n"
+         "                           append sql (including WHERE) to select subset\n"));
     printf(_("  -x, --no-privileges      do not dump privileges (grant/revoke)\n"));
     printf(_("  -X disable-triggers, --disable-triggers\n"
              "                           disable triggers during data-only restore\n"));
@@ -905,16 +913,16 @@
     if (fout->remoteVersion >= 70100)
     {
         appendPQExpBuffer(q, "DECLARE _pg_dump_cursor CURSOR FOR "
-                          "SELECT * FROM ONLY %s",
+                          "SELECT * FROM ONLY %s %s",
                           fmtQualifiedId(tbinfo->relnamespace->nspname,
-                                         classname));
+                                         classname), selectWhere?selectWhere:"");
     }
     else
     {
         appendPQExpBuffer(q, "DECLARE _pg_dump_cursor CURSOR FOR "
-                          "SELECT * FROM %s",
+                          "SELECT * FROM %s %s",
                           fmtQualifiedId(tbinfo->relnamespace->nspname,
-                                         classname));
+                                         classname), selectWhere?selectWhere:"");
     }

     res = PQexec(g_conn, q->data);