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pg_dump: Adjust reltuples from 0 to -1 for dumps of older versions. #9

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Merged
hari90 merged 1 commit into from
May 24, 2025
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pg_dump: Adjust reltuples from 0 to -1 for dumps of older versions. #9

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15 changes: 14 additions & 1 deletion src/bin/pg_dump/pg_dump.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10184,7 +10184,20 @@ dumpRelationStats_dumper(Archive *fout, const void *userArg, const TocEntry *te)
appendStringLiteralAH(out, rsinfo->dobj.name, fout);
appendPQExpBufferStr(out, ",\n");
appendPQExpBuffer(out, "\t'relpages', '%d'::integer,\n", rsinfo->relpages);
appendPQExpBuffer(out, "\t'reltuples', '%s'::real,\n", rsinfo->reltuples);

/*
* Before v14, a reltuples value of 0 was ambiguous: it could either mean
* the relation is empty, or it could mean that it hadn't yet been
* vacuumed or analyzed. (Newer versions use -1 for the latter case.)
* This ambiguity allegedly can cause the planner to choose inefficient
* plans after restoring to v18 or newer. To deal with this, let's just
* set reltuples to -1 in that case.
*/
if (fout->remoteVersion < 140000 && strcmp("0", rsinfo->reltuples) == 0)
appendPQExpBufferStr(out, "\t'reltuples', '-1'::real,\n");
else
appendPQExpBuffer(out, "\t'reltuples', '%s'::real,\n", rsinfo->reltuples);

appendPQExpBuffer(out, "\t'relallvisible', '%d'::integer\n);\n",
rsinfo->relallvisible);

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