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<p>Hi,</p>
<p>It seems that this query has nothing to do with the spatial aspect of Postgis. I therefore recommend to look also at PostgreSQL support channels.</p>
<p>But in general: queries using LIKE, esp. when the wildcard characters are at the beginning or in between, or worst case at the start and end often can't use an index, exp. btree indexes.</p>
<p>Best to avoid LIKE whenever possible and also have a look at pg_trgrm and use a GIST or GIN index.</p>
<p>Have a look at <a href="https://niallburkley.com/blog/index-columns-for-like-in-postgres/">https://niallburkley.com/blog/index-columns-for-like-in-postgres/</a></p>
<p>Greetings,</p>
<p>Andreas</p>
<p id="reply-intro">On 2020-05-22 12:45, postgann2020 s wrote:</p>
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<div dir="ltr"> Hi Team,<br /><br />Thanks for your support.<br /><br />Could someone please suggest on the below query.<br /><br />One of the query which was created on GIS data is taking a long time and even it is not taking the index as well. I have included all the required details for reference.<br /><br /><span style="color: #ff0000;">Database Stack:</span><br />===============<br />PostgreSQL : 9.5.15<br />Postgis: 2.2.7<br /><br /><span style="color: #ff0000;">Table Structure:</span><br />===================<br /><br />ALTER TABLE SCHEMA.TABLE_NAME ADD COLUMN parental_path text;<br /><br /><span style="color: #ff0000;">Created Indexes on column parental_path:</span><br />=================================<br /><br />CREATE INDEX cable_pair_parental_path_idx<br /> ON SCHEMA.TABLE_NAME<br /> USING btree<br /> (md5(parental_path) COLLATE pg_catalog."default");<br /> <br />CREATE INDEX cable_pair_parental_path_idx_fulltext<br /> ON SCHEMA.TABLE_NAME<br /> USING gist<br /> (parental_path COLLATE pg_catalog."default");<br /> <br /><span style="color: #ff0000;">Sample data in "parental_path" column:</span><br />======================================<br /> <br />'route--2309421/2951584/3373649/2511322/1915187/2696397/2623291/2420708/2144348/2294454,circuit--88458/88460,sheath--8874'<br /><br /><span style="color: #ff0000;">Actual Query:</span><br />=============<br /><br />SELECT seq_no + 1 FROM SCHEMA.TABLE_NAME WHERE (parental_path LIKE '%,sheath--' || cable_seq_id || ',%' OR parental_path LIKE 'sheath--' || cable_seq_id || ',%' OR parental_path LIKE '%,sheath--' || cable_seq_id OR parental_path = 'sheath--' || cable_seq_id) ORDER BY seq_no DESC LIMIT 1;<br /><br /><span style="color: #ff0000;">Explain Plan:</span><br />=============<br /><br />Limit (cost=108111.60..108111.61 rows=1 width=4) (actual time=4597.605..4597.605 rows=0 loops=1)<br /> Output: ((seq_no + 1)), seq_no<br /> Buffers: shared hit=2967 read=69606 dirtied=1<br /> -> Sort (cost=108111.60..108113.09 rows=595 width=4) (actual time=4597.603..4597.603 rows=0 loops=1)<br /> Output: ((seq_no + 1)), seq_no<br /> Sort Key: TABLE_NAME.seq_no DESC<br /> Sort Method: quicksort Memory: 25kB<br /> Buffers: shared hit=2967 read=69606 dirtied=1<br /> -> <strong><span style="color: #ff0000;">Seq Scan on SCHEMA.TABLE_NAME (cost=0.00..108108.63 rows=595 width=4) (actual time=4597.595..4597.595 rows=0 loops=1)</span></strong><br /> Output: (seq_no + 1), seq_no<br /> <span style="color: #ff0000;">Filter: ((TABLE_NAME.parental_path ~~ '%,sheath--64690,%'::text) OR (TABLE_NAME.parental_path ~~ 'sheath--64690,%'::text) OR (TABLE_NAME.parental_path ~~ '%,sheath--64690'::text) OR (TABLE_NAME.parental_path = 'sheath--64690'::text))</span><br /> Rows Removed by Filter: 1930188<br /> Buffers: shared hit=2967 read=69606 dirtied=1<br />
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<div>Please share your suggestion.</div>
<div>Thanks & Regards,</div>
<div>PostgAnn.</div>
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