vacuumdb: Don't skip empty relations in --missing-stats-only mode.

nathan-bossart · nathan-bossart · commit 987910502420 · 2025-04-30T14:12:59.000-05:00
Presently, --missing-stats-only skips relations with reltuples set to 0 because empty relations don't get optimizer statistics. However, 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. (Commit 3d351d9 taught v14 and newer to use -1 for the latter case.) This ambiguity can cause --missing-stats-only to inadvertently skip relations that need optimizer statistics after upgrades to v18 and newer (since reltuples is now transferred from the old cluster). To fix, simply remove the check for reltuples != 0. This will cause --missing-stats-only to analyze some empty tables, but that doesn't seem too terrible a trade-off. Reported-by: Christoph Berg <myon@debian.org> Reviewed-by: Christoph Berg <myon@debian.org> Discussion: https://postgr.es/m/aAjyvW5_fRGNr7yF%40msg.df7cb.de
diff --git a/src/bin/scripts/vacuumdb.c b/src/bin/scripts/vacuumdb.c
@@ -954,7 +954,6 @@ retrieve_objects(PGconn *conn, vacuumingOptions *vacopts,
 		appendPQExpBufferStr(&catalog_query,
 							 " EXISTS (SELECT NULL FROM pg_catalog.pg_attribute a\n"
 							 " WHERE a.attrelid OPERATOR(pg_catalog.=) c.oid\n"
-							 " AND c.reltuples OPERATOR(pg_catalog.!=) 0::pg_catalog.float4\n"
 							 " AND a.attnum OPERATOR(pg_catalog.>) 0::pg_catalog.int2\n"
 							 " AND NOT a.attisdropped\n"
 							 " AND a.attstattarget IS DISTINCT FROM 0::pg_catalog.int2\n"
@@ -967,7 +966,6 @@ retrieve_objects(PGconn *conn, vacuumingOptions *vacopts,
 		appendPQExpBufferStr(&catalog_query,
 							 " OR EXISTS (SELECT NULL FROM pg_catalog.pg_statistic_ext e\n"
 							 " WHERE e.stxrelid OPERATOR(pg_catalog.=) c.oid\n"
-							 " AND c.reltuples OPERATOR(pg_catalog.!=) 0::pg_catalog.float4\n"
 							 " AND e.stxstattarget IS DISTINCT FROM 0::pg_catalog.int2\n"
 							 " AND NOT EXISTS (SELECT NULL FROM pg_catalog.pg_statistic_ext_data d\n"
 							 " WHERE d.stxoid OPERATOR(pg_catalog.=) e.oid\n"
@@ -979,7 +977,6 @@ retrieve_objects(PGconn *conn, vacuumingOptions *vacopts,
 							 " JOIN pg_catalog.pg_index i"
 							 " ON i.indexrelid OPERATOR(pg_catalog.=) a.attrelid\n"
 							 " WHERE i.indrelid OPERATOR(pg_catalog.=) c.oid\n"
-							 " AND c.reltuples OPERATOR(pg_catalog.!=) 0::pg_catalog.float4\n"
 							 " AND i.indkey[a.attnum OPERATOR(pg_catalog.-) 1::pg_catalog.int2]"
 							 " OPERATOR(pg_catalog.=) 0::pg_catalog.int2\n"
 							 " AND a.attnum OPERATOR(pg_catalog.>) 0::pg_catalog.int2\n"
@@ -994,7 +991,6 @@ retrieve_objects(PGconn *conn, vacuumingOptions *vacopts,
 		appendPQExpBufferStr(&catalog_query,
 							 " OR EXISTS (SELECT NULL FROM pg_catalog.pg_attribute a\n"
 							 " WHERE a.attrelid OPERATOR(pg_catalog.=) c.oid\n"
-							 " AND c.reltuples OPERATOR(pg_catalog.!=) 0::pg_catalog.float4\n"
 							 " AND a.attnum OPERATOR(pg_catalog.>) 0::pg_catalog.int2\n"
 							 " AND NOT a.attisdropped\n"
 							 " AND a.attstattarget IS DISTINCT FROM 0::pg_catalog.int2\n"
@@ -1011,7 +1007,6 @@ retrieve_objects(PGconn *conn, vacuumingOptions *vacopts,
 		appendPQExpBufferStr(&catalog_query,
 							 " OR EXISTS (SELECT NULL FROM pg_catalog.pg_statistic_ext e\n"
 							 " WHERE e.stxrelid OPERATOR(pg_catalog.=) c.oid\n"
-							 " AND c.reltuples OPERATOR(pg_catalog.!=) 0::pg_catalog.float4\n"
 							 " AND e.stxstattarget IS DISTINCT FROM 0::pg_catalog.int2\n"
 							 " AND c.relhassubclass\n"
 							 " AND NOT p.inherited\n"
