Bug? relpages, reltuples resets to zero
От | jwieck@debis.com (Jan Wieck) |
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Тема | Bug? relpages, reltuples resets to zero |
Дата | |
Msg-id | m0zWQUJ-000EBPC@orion.SAPserv.Hamburg.dsh.de обсуждение исходный текст |
Ответы |
Re: [HACKERS] Bug? relpages, reltuples resets to zero
(Bruce Momjian <maillist@candle.pha.pa.us>)
Re: [HACKERS] Bug? relpages, reltuples resets to zero (Bruce Momjian <maillist@candle.pha.pa.us>) pg_indexes (Bruce Momjian <maillist@candle.pha.pa.us>) |
Список | pgsql-hackers |
Hi, there seems to be a problem with the relation statistics in pg_class. Could someone explain why this happens? doc=> vacuum; VACUUM doc=> select relname, relpages, reltuples from pg_class doc-> where relname = 'doc_wordref'; relname |relpages|reltuples -----------+--------+--------- doc_wordref| 1099| 136027 (1 row) -- ******** That's right doc=> explain select distinct refpage from doc_wordref doc-> where refword ~ '^a'; NOTICE: QUERY PLAN: Unique -> Sort -> Index Scan using doc_wordref_word_idx on doc_wordref EXPLAIN -- ******** As expected doc=> select distinct refpage from doc_wordref doc-> where refword ~ '^a'; refpage ------- 2 3 ... (164 rows) doc=> select relname, relpages, reltuples from pg_class doc-> where relname = 'doc_wordref'; relname |relpages|reltuples -----------+--------+--------- doc_wordref| 0| 0 (1 row) -- ******** Ooops - where are they gone? doc=> explain select distinct refpage from doc_wordref dos-> where refword ~ '^a'; NOTICE: QUERY PLAN: Unique -> Sort -> Index Scan using doc_wordref_word_idx on doc_wordref -- ******** Doesn't matter in the same connection, so reconnect EXPLAIN doc=> \c - connecting to new database: doc doc=> explain select distinct refpage from doc_wordref dos-> where refword ~ '^a'; NOTICE: QUERY PLAN: Unique -> Sort -> Seq Scan on doc_wordref -- ******** Boom EXPLAIN doc=> Why does the SELECT throw away the information about the number of pages and tuples from pg_class? Is this a bug or a feature? If it's a feature, how can I disable it? It is reproduceable. Jan -- #======================================================================# # It's easier to get forgiveness for being wrong than for being right. # # Let's break this rule - forgive me. # #======================================== jwieck@debis.com (Jan Wieck) #
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