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    <pre><code>SET search_path=tmp; -- ------------------------------------------- -- create table and populate it with 10M rows -- ------------------------------------------- DROP SCHEMA tmp CASCADE; CREATE SCHEMA tmp ; SET search_path=tmp; CREATE TABLE old_echo ( the_time timestamp NOT NULL PRIMARY KEY , payload DOUBLE PRECISION NOT NULL ); INSERT INTO old_echo (the_time, payload) SELECT now() - (gs * interval '1 msec') , random() FROM generate_series(1,10000000) gs ; -- DELETE FROM old_echo WHERE random() &lt; 0.8; VACUUM ANALYZE old_echo; SELECT MIN(the_time) AS first , MAX(the_time) AS last , (MAX(the_time) - MIN(the_time))::interval AS width FROM old_echo ; EXPLAIN ANALYZE SELECT * FROM old_echo oe JOIN ( SELECT MIN(the_time) AS first , MAX(the_time) AS last , (MAX(the_time) - MIN(the_time))::interval AS width , ((MAX(the_time) - MIN(the_time))/2)::interval AS half FROM old_echo ) mima ON 1=1 WHERE oe.the_time &gt;= mima.first + mima.half AND oe.the_time &lt; mima.first + mima.half + '1 sec':: interval ; </code></pre> <p>RESULT:</p> <pre><code> QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Nested Loop (cost=0.06..59433.67 rows=1111124 width=64) (actual time=0.101..1.307 rows=1000 loops=1) -&gt; Result (cost=0.06..0.07 rows=1 width=0) (actual time=0.049..0.050 rows=1 loops=1) InitPlan 1 (returns $0) -&gt; Limit (cost=0.00..0.03 rows=1 width=8) (actual time=0.022..0.022 rows=1 loops=1) -&gt; Index Scan using old_echo_pkey on old_echo (cost=0.00..284873.62 rows=10000115 width=8) (actual time=0.021..0.021 rows=1 loops=1) Index Cond: (the_time IS NOT NULL) InitPlan 2 (returns $1) -&gt; Limit (cost=0.00..0.03 rows=1 width=8) (actual time=0.009..0.010 rows=1 loops=1) -&gt; Index Scan Backward using old_echo_pkey on old_echo (cost=0.00..284873.62 rows=10000115 width=8) (actual time=0.009..0.009 rows=1 loops=1) Index Cond: (the_time IS NOT NULL) -&gt; Index Scan using old_echo_pkey on old_echo oe (cost=0.01..34433.30 rows=1111124 width=16) (actual time=0.042..0.764 rows=1000 loops=1) Index Cond: ((the_time &gt;= (($0) + ((($1 - $0) / 2::double precision)))) AND (the_time &lt; ((($0) + ((($1 - $0) / 2::double precision))) + '00:00:01'::interval))) Total runtime: 1.504 ms (13 rows) </code></pre> <p>UPDATE: since the timestamp appears to be non-unique (btw: what do duplicates <em>mean</em> in that case?) I added an extra key column. An ugly hack, but it works here. query time 11ms for 10M -80% rows. (number of rows hit 210/222067):</p> <pre><code>CREATE TABLE old_echo ( the_time timestamp NOT NULL , the_seq SERIAL NOT NULL -- to catch the duplicate keys , payload DOUBLE PRECISION NOT NULL , PRIMARY KEY(the_time, the_seq) ); -- Adding the random will cause some timestamps to be non-unique. -- (and others to be non-existent) INSERT INTO old_echo (the_time, payload) SELECT now() - ((gs+random()*1000::integer) * interval '1 msec') , random() FROM generate_series(1,10000000) gs ; DELETE FROM old_echo WHERE random() &lt; 0.8; </code></pre>
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    1. POSlow query time in postgresql when UTC milliseconds is stored as bigint
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    1. USwildplasser
    1. USwildplasser
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    1. COBTW: I reran the same query with 100M rows * 20%, and it completed in 19 ms, yielding 205 rows.
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    2. CO@wildpasser - Thank you for the test code. The results looks amazing. I will make the changes as per your suggestions and post my results today.
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    3. CO@wildpasser - The time is not unique in my case. So, can't use it as primary key.
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