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: http://www.sai.msu.su/~megera/postgres/gist/tsearch/V2/docs/oscon_tsearch2/readme_overview_06.html
Дата изменения: Unknown Дата индексирования: Sat Dec 22 10:29:14 2007 Кодировка: |
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Tsearch2 README File Example: Overview (Continued)Because an index has not been defined, the previous query is searching using a sequential scan over each row. This will be slow for large tables. VACUUM FULL ANALYZE; EXPLAIN ANAYLZE SELECT *, rank(ts_vec, to_tsquery('default', 'database | query')) FROM ts_readme WHERE ts_vec @@ to_tsquery('default', 'database | query') ORDER BY rank(ts_vec, to_tsquery('default', 'database | query')) DESC LIMIT 5; QUERY PLAN ----------------------------------------------------------------------------------------------------------------- Limit (cost=7.64..7.64 rows=1 width=89) (actual time=0.440..0.455 rows=5 loops=1) -> Sort (cost=7.64..7.64 rows=1 width=89) (actual time=0.435..0.440 rows=5 loops=1) Sort Key: rank(ts_vec, '\'databas\' | \'queri\''::tsquery) -> Seq Scan on ts_readme (cost=0.00..7.63 rows=1 width=89) (actual time=0.117..0.391 rows=11 loops=1) Filter: (ts_vec @@ '\'databas\' | \'queri\''::tsquery) Total runtime: 0.516 ms |