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Use binary search instead of brute-force scan in findNamespace().

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The previous coding presented a significant bottleneck when dumping
databases containing many thousands of schemas, since the total time
spent searching would increase roughly as O(N^2) in the number of objects.
Noted by Jeff Janes, though I rewrote his proposed patch to use the
existing findObjectByOid infrastructure.

Since this is a longstanding performance bug, backpatch to all supported
versions.
This commit is contained in:
Tom Lane
2012-05-25 14:35:37 -04:00
parent 45ca31d6a7
commit 73cc7d3b24
3 changed files with 31 additions and 23 deletions
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35
src/bin/pg_dump/pg_dump.c
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@@ -129,10 +129,6 @@ char g_comment_end[10];
static const CatalogId nilCatalogId = {0, 0};
/* these are to avoid passing around info for findNamespace() */
static NamespaceInfo *g_namespaces;
static int g_numNamespaces;
/* flags for various command-line long options */
static int binary_upgrade = 0;
static int disable_dollar_quoting = 0;
@@ -2595,8 +2591,7 @@ getNamespaces(Archive *fout, int *numNamespaces)
selectDumpableNamespace(&nsinfo[1]);
g_namespaces = nsinfo;
g_numNamespaces = *numNamespaces = 2;
*numNamespaces = 2;
return nsinfo;
}
@@ -2648,8 +2643,7 @@ getNamespaces(Archive *fout, int *numNamespaces)
PQclear(res);
destroyPQExpBuffer(query);
g_namespaces = nsinfo;
g_numNamespaces = *numNamespaces = ntups;
*numNamespaces = ntups;
return nsinfo;
}
@@ -2660,35 +2654,34 @@ getNamespaces(Archive *fout, int *numNamespaces)
* getNamespaces
*
* NB: for pre-7.3 source database, we use object OID to guess whether it's
* a system object or not. In 7.3 and later there is no guessing.
* a system object or not. In 7.3 and later there is no guessing, and we
* don't use objoid at all.
*/
static NamespaceInfo *
findNamespace(Archive *fout, Oid nsoid, Oid objoid)
{
int i;
NamespaceInfo *nsinfo;
if (fout->remoteVersion >= 70300)
{
for (i = 0; i < g_numNamespaces; i++)
{
NamespaceInfo *nsinfo = &g_namespaces[i];
if (nsoid == nsinfo->dobj.catId.oid)
return nsinfo;
}
exit_horribly(NULL, "schema with OID %u does not exist\n", nsoid);
nsinfo = findNamespaceByOid(nsoid);
}
else
{
/* This code depends on the layout set up by getNamespaces. */
/* This code depends on the dummy objects set up by getNamespaces. */
Oid i;
if (objoid > g_last_builtin_oid)
i = 0; /* user object */
else
i = 1; /* system object */
return &g_namespaces[i];
nsinfo = findNamespaceByOid(i);
}
return NULL; /* keep compiler quiet */
if (nsinfo == NULL)
exit_horribly(NULL, "schema with OID %u does not exist\n", nsoid);
return nsinfo;
}
/*