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Rewrite pg_dump's comment-dumping code to pull over all the comments
in one query, rather than making a separate query for each object that could have a comment. This costs relatively little space (a few tens of K typically) and saves substantial time in databases with many objects. I find it reduces the runtime of 'pg_dump -s regression' by about a third.
This commit is contained in:
Tom Lane
parent
c8aaa5ceec
commit
05649b88c7
@ -12,7 +12,7 @@
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* by PostgreSQL
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/bin/pg_dump/pg_dump.c,v 1.367 2004/03/03 21:28:54 tgl Exp $
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* $PostgreSQL: pgsql/src/bin/pg_dump/pg_dump.c,v 1.368 2004/03/20 20:09:45 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -67,6 +67,15 @@ extern int optind,
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opterr;
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typedef struct
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{
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const char *descr; /* comment for an object */
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Oid classoid; /* object class (catalog OID) */
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Oid objoid; /* object OID */
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int objsubid; /* subobject (table column #) */
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} CommentItem;
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/* global decls */
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bool g_verbose; /* User wants verbose narration of our
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* activities. */
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@ -105,6 +114,9 @@ static void dumpTableData(Archive *fout, TableDataInfo *tdinfo);
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static void dumpComment(Archive *fout, const char *target,
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const char *namespace, const char *owner,
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CatalogId catalogId, int subid, DumpId dumpId);
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static int findComments(Archive *fout, Oid classoid, Oid objoid,
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CommentItem **items);
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static int collectComments(Archive *fout, CommentItem **items);
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static void dumpDumpableObject(Archive *fout, DumpableObject *dobj);
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static void dumpNamespace(Archive *fout, NamespaceInfo *nspinfo);
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static void dumpType(Archive *fout, TypeInfo *tinfo);
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@ -3880,58 +3892,33 @@ dumpComment(Archive *fout, const char *target,
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const char *namespace, const char *owner,
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CatalogId catalogId, int subid, DumpId dumpId)
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{
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PGresult *res;
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PQExpBuffer query;
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int i_description;
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CommentItem *comments;
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int ncomments;
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/* Comments are SCHEMA not data */
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if (dataOnly)
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return;
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/*
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* Note we do NOT change source schema here; preserve the caller's
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* setting, instead.
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*/
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/* Search for comments associated with catalogId, using table */
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ncomments = findComments(fout, catalogId.tableoid, catalogId.oid,
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&comments);
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/* Build query to find comment */
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query = createPQExpBuffer();
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if (fout->remoteVersion >= 70300)
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/* Is there one matching the subid? */
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while (ncomments > 0)
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{
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appendPQExpBuffer(query,
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"SELECT description FROM pg_catalog.pg_description "
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"WHERE classoid = '%u'::pg_catalog.oid and "
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"objoid = '%u'::pg_catalog.oid and objsubid = %d",
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catalogId.tableoid, catalogId.oid, subid);
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if (comments->objsubid == subid)
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break;
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comments++;
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ncomments--;
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}
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else if (fout->remoteVersion >= 70200)
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{
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appendPQExpBuffer(query,
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"SELECT description FROM pg_description "
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"WHERE classoid = '%u'::oid and "
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"objoid = '%u'::oid and objsubid = %d",
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catalogId.tableoid, catalogId.oid, subid);
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}
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else
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{
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/* Note: this will fail to find attribute comments in pre-7.2... */
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appendPQExpBuffer(query, "SELECT description FROM pg_description WHERE objoid = '%u'::oid", catalogId.oid);
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}
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/* Execute query */
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res = PQexec(g_conn, query->data);
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check_sql_result(res, g_conn, query->data, PGRES_TUPLES_OK);
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/* If a comment exists, build COMMENT ON statement */
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if (PQntuples(res) == 1)
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if (ncomments > 0)
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{
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i_description = PQfnumber(res, "description");
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resetPQExpBuffer(query);
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PQExpBuffer query = createPQExpBuffer();
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appendPQExpBuffer(query, "COMMENT ON %s IS ", target);
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appendStringLiteral(query, PQgetvalue(res, 0, i_description), false);
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appendStringLiteral(query, comments->descr, false);
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appendPQExpBuffer(query, ";\n");
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ArchiveEntry(fout, nilCatalogId, createDumpId(),
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@ -3939,82 +3926,47 @@ dumpComment(Archive *fout, const char *target,
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"COMMENT", query->data, "", NULL,
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&(dumpId), 1,
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NULL, NULL);
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}
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PQclear(res);
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destroyPQExpBuffer(query);
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destroyPQExpBuffer(query);
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}
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}
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/*
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* dumpTableComment --
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*
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* As above, but dump comments for both the specified table (or view)
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* and its columns. For speed, we want to do this with only one query.
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* and its columns.
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*/
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static void
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dumpTableComment(Archive *fout, TableInfo *tbinfo,
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const char *reltypename)
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{
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PGresult *res;
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CommentItem *comments;
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int ncomments;
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PQExpBuffer query;
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PQExpBuffer target;
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int i_description;
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int i_objsubid;
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int ntups;
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int i;
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/* Comments are SCHEMA not data */
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if (dataOnly)
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return;
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/*
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* Note we do NOT change source schema here; preserve the caller's
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* setting, instead.
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*/
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/* Search for comments associated with relation, using table */
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ncomments = findComments(fout,
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tbinfo->dobj.catId.tableoid,
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tbinfo->dobj.catId.oid,
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&comments);
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/* Build query to find comments */
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/* If comments exist, build COMMENT ON statements */
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if (ncomments <= 0)
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return;
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query = createPQExpBuffer();
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target = createPQExpBuffer();
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if (fout->remoteVersion >= 70300)
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while (ncomments > 0)
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{
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appendPQExpBuffer(query, "SELECT description, objsubid FROM pg_catalog.pg_description "
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"WHERE classoid = '%u'::pg_catalog.oid and "
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"objoid = '%u'::pg_catalog.oid "
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"ORDER BY objoid, classoid, objsubid",
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tbinfo->dobj.catId.tableoid, tbinfo->dobj.catId.oid);
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}
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else if (fout->remoteVersion >= 70200)
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{
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appendPQExpBuffer(query, "SELECT description, objsubid FROM pg_description "
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"WHERE classoid = '%u'::oid and "
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"objoid = '%u'::oid "
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"ORDER BY objoid, classoid, objsubid",
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tbinfo->dobj.catId.tableoid, tbinfo->dobj.catId.oid);
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}
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else
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{
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/* Note: this will fail to find attribute comments in pre-7.2... */
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appendPQExpBuffer(query, "SELECT description, 0 as objsubid FROM pg_description WHERE objoid = '%u'::oid",
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tbinfo->dobj.catId.oid);
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}
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/* Execute query */
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res = PQexec(g_conn, query->data);
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check_sql_result(res, g_conn, query->data, PGRES_TUPLES_OK);
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i_description = PQfnumber(res, "description");
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i_objsubid = PQfnumber(res, "objsubid");
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/* If comments exist, build COMMENT ON statements */
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ntups = PQntuples(res);
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for (i = 0; i < ntups; i++)
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{
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const char *descr = PQgetvalue(res, i, i_description);
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int objsubid = atoi(PQgetvalue(res, i, i_objsubid));
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const char *descr = comments->descr;
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int objsubid = comments->objsubid;
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if (objsubid == 0)
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{
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@ -4054,13 +4006,183 @@ dumpTableComment(Archive *fout, TableInfo *tbinfo,
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&(tbinfo->dobj.dumpId), 1,
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NULL, NULL);
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}
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comments++;
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ncomments--;
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}
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PQclear(res);
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destroyPQExpBuffer(query);
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destroyPQExpBuffer(target);
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}
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/*
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* findComments --
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*
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* Find the comment(s), if any, associated with the given object. All the
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* objsubid values associated with the given classoid/objoid are found with
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* one search.
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*/
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static int
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findComments(Archive *fout, Oid classoid, Oid objoid,
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CommentItem **items)
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{
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/* static storage for table of comments */
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static CommentItem *comments = NULL;
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static int ncomments = -1;
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CommentItem *middle = NULL;
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CommentItem *low;
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CommentItem *high;
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int nmatch;
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/* Get comments if we didn't already */
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if (ncomments < 0)
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ncomments = collectComments(fout, &comments);
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/*
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* Pre-7.2, pg_description does not contain classoid, so collectComments
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* just stores a zero. If there's a collision on object OID, well, you
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* get duplicate comments.
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*/
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if (fout->remoteVersion < 70200)
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classoid = 0;
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/*
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* Do binary search to find some item matching the object.
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*/
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low = &comments[0];
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high = &comments[ncomments-1];
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while (low <= high)
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{
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middle = low + (high - low) / 2;
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if (classoid < middle->classoid)
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high = middle - 1;
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else if (classoid > middle->classoid)
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low = middle + 1;
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else if (objoid < middle->objoid)
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high = middle - 1;
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else if (objoid > middle->objoid)
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low = middle + 1;
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else
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break; /* found a match */
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}
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if (low > high) /* no matches */
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{
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*items = NULL;
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return 0;
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}
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/*
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* Now determine how many items match the object. The search loop
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* invariant still holds: only items between low and high inclusive
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* could match.
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*/
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nmatch = 1;
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while (middle > low)
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{
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if (classoid != middle[-1].classoid ||
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objoid != middle[-1].objoid)
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break;
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middle--;
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nmatch++;
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}
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*items = middle;
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middle += nmatch;
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while (middle <= high)
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{
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if (classoid != middle->classoid ||
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objoid != middle->objoid)
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break;
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middle++;
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nmatch++;
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}
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return nmatch;
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}
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/*
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* collectComments --
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*
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* Construct a table of all comments available for database objects.
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* We used to do per-object queries for the comments, but it's much faster
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* to pull them all over at once, and on most databases the memory cost
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* isn't high.
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*
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* The table is sorted by classoid/objid/objsubid for speed in lookup.
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*/
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static int
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collectComments(Archive *fout, CommentItem **items)
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{
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PGresult *res;
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PQExpBuffer query;
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int i_description;
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int i_classoid;
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int i_objoid;
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int i_objsubid;
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int ntups;
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int i;
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CommentItem *comments;
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/*
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* Note we do NOT change source schema here; preserve the caller's
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* setting, instead.
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*/
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query = createPQExpBuffer();
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if (fout->remoteVersion >= 70300)
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{
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appendPQExpBuffer(query, "SELECT description, classoid, objoid, objsubid "
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"FROM pg_catalog.pg_description "
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"ORDER BY classoid, objoid, objsubid");
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}
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else if (fout->remoteVersion >= 70200)
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{
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appendPQExpBuffer(query, "SELECT description, classoid, objoid, objsubid "
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"FROM pg_description "
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"ORDER BY classoid, objoid, objsubid");
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}
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else
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{
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/* Note: this will fail to find attribute comments in pre-7.2... */
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appendPQExpBuffer(query, "SELECT description, 0 as classoid, objoid, 0 as objsubid "
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"FROM pg_description "
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"ORDER BY objoid");
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}
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res = PQexec(g_conn, query->data);
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check_sql_result(res, g_conn, query->data, PGRES_TUPLES_OK);
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/* Construct lookup table containing OIDs in numeric form */
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i_description = PQfnumber(res, "description");
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i_classoid = PQfnumber(res, "classoid");
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i_objoid = PQfnumber(res, "objoid");
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i_objsubid = PQfnumber(res, "objsubid");
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ntups = PQntuples(res);
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comments = (CommentItem *) malloc(ntups * sizeof(CommentItem));
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for (i = 0; i < ntups; i++)
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{
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comments[i].descr = PQgetvalue(res, i, i_description);
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comments[i].classoid = atooid(PQgetvalue(res, i, i_classoid));
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comments[i].objoid = atooid(PQgetvalue(res, i, i_objoid));
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comments[i].objsubid = atoi(PQgetvalue(res, i, i_objsubid));
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}
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/* Do NOT free the PGresult since we are keeping pointers into it */
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destroyPQExpBuffer(query);
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*items = comments;
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return ntups;
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}
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/*
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* dumpDumpableObject
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*
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