Hello, We face in a PostgreSQL 11.4 installation on a potent Linux host a serious performance degree. A SELECT with a LIKE clause on a table with ca. 5.200.000 rows on a column with an Index ignores this and does a full table scan: sisis=# explain (analyze, buffers) select * from d01buch where d01ort like 'Z 9610%' ; QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------- Gather (cost=1000.00..680262.71 rows=510 width=952) (actual time=1324.096..1349.429 rows=1 loops=1) Workers Planned: 4 Workers Launched: 4 Buffers: shared hit=102040 read=560674 -> Parallel Seq Scan on d01buch (cost=0.00..679211.71 rows=128 width=952) (actual time=1117.663..1315.062 rows=0 loops=5) Filter: (d01ort ~~ 'Z 9610%'::text) Rows Removed by Filter: 1055853 Buffers: shared hit=102040 read=560674 Planning Time: 2.028 ms Execution Time: 1349.593 ms (10 Zeilen) Why is this (ignoring the Index) and what could be done? Thanks matthias -- Matthias Apitz, ✉ guru@xxxxxxxxxxx, http://www.unixarea.de/ +49-176-38902045 Public GnuPG key: http://www.unixarea.de/key.pub
