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@ -229,14 +229,12 @@ |
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The bugs mailing list is available. To subscribe to this list, send |
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The bugs mailing list is available. To subscribe to this list, send |
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email to pgsql-bugs-request@PostgreSQL.org with a body of: |
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email to pgsql-bugs-request@PostgreSQL.org with a body of: |
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subscribe |
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subscribe |
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end |
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end |
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There is also a developers discussion mailing list available. To |
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There is also a developers discussion mailing list available. To |
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subscribe to this list, send email to |
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subscribe to this list, send email to |
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pgsql-hackers-request@PostgreSQL.org with a body of: |
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pgsql-hackers-request@PostgreSQL.org with a body of: |
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subscribe |
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subscribe |
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end |
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end |
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@ -964,19 +962,19 @@ BYTEA bytea variable-length byte array (null-safe) |
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4.22) How do I create a column that will default to the current time? |
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4.22) How do I create a column that will default to the current time? |
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Use now(): |
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Use now(): |
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CREATE TABLE test (x int, modtime timestamp DEFAULT now() ); |
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CREATE TABLE test (x int, modtime timestamp DEFAULT now() ); |
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4.23) Why are my subqueries using IN so slow? |
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4.23) Why are my subqueries using IN so slow? |
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Currently, we join subqueries to outer queries by sequentially |
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Currently, we join subqueries to outer queries by sequentially |
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scanning the result of the subquery for each row of the outer query. A |
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scanning the result of the subquery for each row of the outer query. A |
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workaround is to replace IN with EXISTS: |
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workaround is to replace IN with EXISTS: |
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SELECT * |
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SELECT * |
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FROM tab |
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FROM tab |
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WHERE col1 IN (SELECT col2 FROM TAB2) |
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WHERE col1 IN (SELECT col2 FROM TAB2) |
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to: |
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to: |
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SELECT * |
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SELECT * |
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FROM tab |
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FROM tab |
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WHERE EXISTS (SELECT col2 FROM TAB2 WHERE col1 = col2) |
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WHERE EXISTS (SELECT col2 FROM TAB2 WHERE col1 = col2) |
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