Full-text search runs slow on single rare word but runs fast when same word repeated?
I have a table with a GIN index similar to:
CREATE INDEX my_index ON my_table USING GIN (to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )))
where source = 'x';
My table has 2.5M rows.
Suppose I want to query for the word banana, which is not a very common word in this dataset. In fact, it appears exactly 8 times.
Now here's the weird part.
This query takes a repeatable 3 full seconds to execute:
select * from my_table where
(source='x' AND plainto_tsquery('english', 'banana') @@ to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )) AND (jsondoc->>'L_AskingPrice')::real>=250000 AND ((jsondoc->>'L_AskingPrice')::real<=2500000 OR (jsondoc->>'L_asking_price_low')::real<=2500000) AND jsondoc->>
'L_Status' IN ('ACTIVE','BACK ON MARKET') AND iscurrent='true')
while this executes reliably in just under 50 milliseconds:
select * from my_table where
(source='x' AND plainto_tsquery('english', 'banana banana') @@ to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )) AND (jsondoc->>'L_AskingPrice')::real>=250000 AND ((jsondoc->>'L_AskingPrice')::real<=2500000 OR (jsondoc->>'L_asking_price_low')::real<=2500000) AND jsondoc->>
'L_Status' IN ('ACTIVE','BACK ON MARKET') AND iscurrent='true')
Can you spot the difference?
Yes: the word banana is repeated in the second query. Now, this is just an example. Through additional testing, I found that essentially any single word takes a long time (~3 seconds), while any double-word search (including, 2 different words) runs fast (~50ms).
PostgreSQL version is the latest (v11).
What could cause this?
Query Plans
Slow (one word)
Fast (one word repeated twice)
postgresql query-optimization
asked Nov 17 '18 at 10:31
Alex R
4,106104798
|
show 4 more comments
I have a table with a GIN index similar to:
CREATE INDEX my_index ON my_table USING GIN (to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )))
where source = 'x';
My table has 2.5M rows.
Suppose I want to query for the word banana, which is not a very common word in this dataset. In fact, it appears exactly 8 times.
Now here's the weird part.
This query takes a repeatable 3 full seconds to execute:
select * from my_table where
(source='x' AND plainto_tsquery('english', 'banana') @@ to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )) AND (jsondoc->>'L_AskingPrice')::real>=250000 AND ((jsondoc->>'L_AskingPrice')::real<=2500000 OR (jsondoc->>'L_asking_price_low')::real<=2500000) AND jsondoc->>
'L_Status' IN ('ACTIVE','BACK ON MARKET') AND iscurrent='true')
while this executes reliably in just under 50 milliseconds:
select * from my_table where
(source='x' AND plainto_tsquery('english', 'banana banana') @@ to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )) AND (jsondoc->>'L_AskingPrice')::real>=250000 AND ((jsondoc->>'L_AskingPrice')::real<=2500000 OR (jsondoc->>'L_asking_price_low')::real<=2500000) AND jsondoc->>
'L_Status' IN ('ACTIVE','BACK ON MARKET') AND iscurrent='true')
Can you spot the difference?
Yes: the word banana is repeated in the second query. Now, this is just an example. Through additional testing, I found that essentially any single word takes a long time (~3 seconds), while any double-word search (including, 2 different words) runs fast (~50ms).
PostgreSQL version is the latest (v11).
What could cause this?
Query Plans
Slow (one word)
Fast (one word repeated twice)
postgresql query-optimization
asked Nov 17 '18 at 10:31
Alex R
4,106104798
2
Difficult to say since you've kept the EXPLAIN ANALYSE output hidden from everyone.
– Richard Huxton
Nov 17 '18 at 11:08
@RichardHuxton see updates
– Alex R
Nov 17 '18 at 16:53
Excellent question. But plaease provide data (incl. query plans) as text, never as image. The lines are truncated, too.
– Erwin Brandstetter
Nov 17 '18 at 17:19
How? I’m using pgAdmin, there is no option to copy as text.
– Alex R
Nov 17 '18 at 17:20
You can just select and copy the output fromEXPLAIN (ANALYZE, BUFFERS) SELECT...in pgAdmin3, pgAdmin4 or psql (or any other client).
– Erwin Brandstetter
Nov 17 '18 at 18:02
|
show 4 more comments
I have a table with a GIN index similar to:
CREATE INDEX my_index ON my_table USING GIN (to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )))
where source = 'x';
My table has 2.5M rows.
Suppose I want to query for the word banana, which is not a very common word in this dataset. In fact, it appears exactly 8 times.
Now here's the weird part.
This query takes a repeatable 3 full seconds to execute:
select * from my_table where
(source='x' AND plainto_tsquery('english', 'banana') @@ to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )) AND (jsondoc->>'L_AskingPrice')::real>=250000 AND ((jsondoc->>'L_AskingPrice')::real<=2500000 OR (jsondoc->>'L_asking_price_low')::real<=2500000) AND jsondoc->>
'L_Status' IN ('ACTIVE','BACK ON MARKET') AND iscurrent='true')
while this executes reliably in just under 50 milliseconds:
select * from my_table where
(source='x' AND plainto_tsquery('english', 'banana banana') @@ to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )) AND (jsondoc->>'L_AskingPrice')::real>=250000 AND ((jsondoc->>'L_AskingPrice')::real<=2500000 OR (jsondoc->>'L_asking_price_low')::real<=2500000) AND jsondoc->>
'L_Status' IN ('ACTIVE','BACK ON MARKET') AND iscurrent='true')
Can you spot the difference?
Yes: the word banana is repeated in the second query. Now, this is just an example. Through additional testing, I found that essentially any single word takes a long time (~3 seconds), while any double-word search (including, 2 different words) runs fast (~50ms).
PostgreSQL version is the latest (v11).
What could cause this?
Query Plans
Slow (one word)
Fast (one word repeated twice)
postgresql query-optimization
asked Nov 17 '18 at 10:31
Alex R
4,106104798
I have a table with a GIN index similar to:
CREATE INDEX my_index ON my_table USING GIN (to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )))
where source = 'x';
My table has 2.5M rows.
Suppose I want to query for the word banana, which is not a very common word in this dataset. In fact, it appears exactly 8 times.
Now here's the weird part.
This query takes a repeatable 3 full seconds to execute:
select * from my_table where
(source='x' AND plainto_tsquery('english', 'banana') @@ to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )) AND (jsondoc->>'L_AskingPrice')::real>=250000 AND ((jsondoc->>'L_AskingPrice')::real<=2500000 OR (jsondoc->>'L_asking_price_low')::real<=2500000) AND jsondoc->>
'L_Status' IN ('ACTIVE','BACK ON MARKET') AND iscurrent='true')
while this executes reliably in just under 50 milliseconds:
select * from my_table where
(source='x' AND plainto_tsquery('english', 'banana banana') @@ to_tsvector('english', lower(
(jsondoc->>'StreetAddress')
|| ' ' || (jsondoc->>'Neighborhood')
|| ' ' || (jsondoc->>'Area')
|| ' ' || (jsondoc->>'CrossStreet')
|| ' ' || (jsondoc->>'Community')
|| ' ' || (jsondoc->>'Complex') )) AND (jsondoc->>'L_AskingPrice')::real>=250000 AND ((jsondoc->>'L_AskingPrice')::real<=2500000 OR (jsondoc->>'L_asking_price_low')::real<=2500000) AND jsondoc->>
'L_Status' IN ('ACTIVE','BACK ON MARKET') AND iscurrent='true')
Can you spot the difference?
Yes: the word banana is repeated in the second query. Now, this is just an example. Through additional testing, I found that essentially any single word takes a long time (~3 seconds), while any double-word search (including, 2 different words) runs fast (~50ms).
PostgreSQL version is the latest (v11).
What could cause this?
Query Plans
Slow (one word)
Fast (one word repeated twice)
postgresql query-optimization
postgresql query-optimization
asked Nov 17 '18 at 10:31
Alex R
4,106104798
asked Nov 17 '18 at 10:31
Alex R
4,106104798
edited Nov 17 '18 at 16:53
asked Nov 17 '18 at 10:31
Alex R
4,106104798
asked Nov 17 '18 at 10:31
Alex R
4,106104798
asked Nov 17 '18 at 10:31
Alex R
4,106104798
4,106104798
2
Difficult to say since you've kept the EXPLAIN ANALYSE output hidden from everyone.
– Richard Huxton
Nov 17 '18 at 11:08
@RichardHuxton see updates
– Alex R
Nov 17 '18 at 16:53
Excellent question. But plaease provide data (incl. query plans) as text, never as image. The lines are truncated, too.
– Erwin Brandstetter
Nov 17 '18 at 17:19
How? I’m using pgAdmin, there is no option to copy as text.
– Alex R
Nov 17 '18 at 17:20
You can just select and copy the output fromEXPLAIN (ANALYZE, BUFFERS) SELECT...in pgAdmin3, pgAdmin4 or psql (or any other client).
– Erwin Brandstetter
Nov 17 '18 at 18:02
|
show 4 more comments
2
Difficult to say since you've kept the EXPLAIN ANALYSE output hidden from everyone.
– Richard Huxton
Nov 17 '18 at 11:08
@RichardHuxton see updates
– Alex R
Nov 17 '18 at 16:53
Excellent question. But plaease provide data (incl. query plans) as text, never as image. The lines are truncated, too.
– Erwin Brandstetter
Nov 17 '18 at 17:19
How? I’m using pgAdmin, there is no option to copy as text.
– Alex R
Nov 17 '18 at 17:20
You can just select and copy the output fromEXPLAIN (ANALYZE, BUFFERS) SELECT...in pgAdmin3, pgAdmin4 or psql (or any other client).
– Erwin Brandstetter
Nov 17 '18 at 18:02
2
2
Difficult to say since you've kept the EXPLAIN ANALYSE output hidden from everyone.
– Richard Huxton
Nov 17 '18 at 11:08
Difficult to say since you've kept the EXPLAIN ANALYSE output hidden from everyone.
– Richard Huxton
Nov 17 '18 at 11:08
@RichardHuxton see updates
– Alex R
Nov 17 '18 at 16:53
@RichardHuxton see updates
– Alex R
Nov 17 '18 at 16:53
Excellent question. But plaease provide data (incl. query plans) as text, never as image. The lines are truncated, too.
– Erwin Brandstetter
Nov 17 '18 at 17:19
Excellent question. But plaease provide data (incl. query plans) as text, never as image. The lines are truncated, too.
– Erwin Brandstetter
Nov 17 '18 at 17:19
How? I’m using pgAdmin, there is no option to copy as text.
– Alex R
Nov 17 '18 at 17:20
How? I’m using pgAdmin, there is no option to copy as text.
– Alex R
Nov 17 '18 at 17:20
You can just select and copy the output from
EXPLAIN (ANALYZE, BUFFERS) SELECT... in pgAdmin3, pgAdmin4 or psql (or any other client).– Erwin Brandstetter
Nov 17 '18 at 18:02
You can just select and copy the output from
EXPLAIN (ANALYZE, BUFFERS) SELECT... in pgAdmin3, pgAdmin4 or psql (or any other client).– Erwin Brandstetter
Nov 17 '18 at 18:02
|
show 4 more comments
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2
Difficult to say since you've kept the EXPLAIN ANALYSE output hidden from everyone.
– Richard Huxton
Nov 17 '18 at 11:08
@RichardHuxton see updates
– Alex R
Nov 17 '18 at 16:53
Excellent question. But plaease provide data (incl. query plans) as text, never as image. The lines are truncated, too.
– Erwin Brandstetter
Nov 17 '18 at 17:19
How? I’m using pgAdmin, there is no option to copy as text.
– Alex R
Nov 17 '18 at 17:20
You can just select and copy the output from
EXPLAIN (ANALYZE, BUFFERS) SELECT...in pgAdmin3, pgAdmin4 or psql (or any other client).– Erwin Brandstetter
Nov 17 '18 at 18:02