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c11453ce0a
The warning about hash indexes not being write-ahead logged and their use being discouraged has been removed. "snapshot too old" is now supported for tables with hash indexes. Most importantly, barring bugs, hash indexes will now be crash-safe and usable on standbys. This commit doesn't yet add WAL consistency checking for hash indexes, as we now have for other index types; a separate patch has been submitted to cure that lack. Amit Kapila, reviewed and slightly modified by me. The larger patch series of which this is a part has been reviewed and tested by Álvaro Herrera, Ashutosh Sharma, Mark Kirkwood, Jeff Janes, and Jesper Pedersen. Discussion: http://postgr.es/m/CAA4eK1JOBX=YU33631Qh-XivYXtPSALh514+jR8XeD7v+K3r_Q@mail.gmail.com
163 lines
6.1 KiB
Plaintext
163 lines
6.1 KiB
Plaintext
CREATE TABLE test_hash (a int, b text);
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INSERT INTO test_hash VALUES (1, 'one');
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CREATE INDEX test_hash_a_idx ON test_hash USING hash (a);
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\x
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SELECT hash_page_type(get_raw_page('test_hash_a_idx', 0));
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-[ RECORD 1 ]--+---------
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hash_page_type | metapage
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SELECT hash_page_type(get_raw_page('test_hash_a_idx', 1));
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-[ RECORD 1 ]--+-------
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hash_page_type | bucket
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SELECT hash_page_type(get_raw_page('test_hash_a_idx', 2));
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-[ RECORD 1 ]--+-------
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hash_page_type | bucket
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SELECT hash_page_type(get_raw_page('test_hash_a_idx', 3));
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-[ RECORD 1 ]--+-------
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hash_page_type | bucket
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SELECT hash_page_type(get_raw_page('test_hash_a_idx', 4));
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-[ RECORD 1 ]--+-------
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hash_page_type | bucket
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SELECT hash_page_type(get_raw_page('test_hash_a_idx', 5));
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-[ RECORD 1 ]--+-------
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hash_page_type | bitmap
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SELECT hash_page_type(get_raw_page('test_hash_a_idx', 6));
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ERROR: block number 6 is out of range for relation "test_hash_a_idx"
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SELECT * FROM hash_bitmap_info('test_hash_a_idx', 0);
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ERROR: invalid overflow block number 0
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SELECT * FROM hash_bitmap_info('test_hash_a_idx', 1);
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ERROR: invalid overflow block number 1
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SELECT * FROM hash_bitmap_info('test_hash_a_idx', 2);
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ERROR: invalid overflow block number 2
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SELECT * FROM hash_bitmap_info('test_hash_a_idx', 3);
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ERROR: invalid overflow block number 3
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SELECT * FROM hash_bitmap_info('test_hash_a_idx', 4);
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ERROR: invalid overflow block number 4
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SELECT * FROM hash_bitmap_info('test_hash_a_idx', 5);
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ERROR: invalid overflow block number 5
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SELECT magic, version, ntuples, bsize, bmsize, bmshift, maxbucket, highmask,
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lowmask, ovflpoint, firstfree, nmaps, procid, spares, mapp FROM
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hash_metapage_info(get_raw_page('test_hash_a_idx', 0));
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-[ RECORD 1 ]----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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magic | 105121344
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version | 2
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ntuples | 1
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bsize | 8152
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bmsize | 4096
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bmshift | 15
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maxbucket | 3
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highmask | 7
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lowmask | 3
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ovflpoint | 2
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firstfree | 0
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nmaps | 1
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procid | 450
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spares | {0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
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mapp | {5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
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SELECT magic, version, ntuples, bsize, bmsize, bmshift, maxbucket, highmask,
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lowmask, ovflpoint, firstfree, nmaps, procid, spares, mapp FROM
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hash_metapage_info(get_raw_page('test_hash_a_idx', 1));
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ERROR: page is not a hash meta page
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SELECT magic, version, ntuples, bsize, bmsize, bmshift, maxbucket, highmask,
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lowmask, ovflpoint, firstfree, nmaps, procid, spares, mapp FROM
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hash_metapage_info(get_raw_page('test_hash_a_idx', 2));
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ERROR: page is not a hash meta page
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SELECT magic, version, ntuples, bsize, bmsize, bmshift, maxbucket, highmask,
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lowmask, ovflpoint, firstfree, nmaps, procid, spares, mapp FROM
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hash_metapage_info(get_raw_page('test_hash_a_idx', 3));
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ERROR: page is not a hash meta page
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SELECT magic, version, ntuples, bsize, bmsize, bmshift, maxbucket, highmask,
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lowmask, ovflpoint, firstfree, nmaps, procid, spares, mapp FROM
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hash_metapage_info(get_raw_page('test_hash_a_idx', 4));
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ERROR: page is not a hash meta page
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SELECT magic, version, ntuples, bsize, bmsize, bmshift, maxbucket, highmask,
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lowmask, ovflpoint, firstfree, nmaps, procid, spares, mapp FROM
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hash_metapage_info(get_raw_page('test_hash_a_idx', 5));
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ERROR: page is not a hash meta page
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SELECT live_items, dead_items, page_size, hasho_prevblkno, hasho_nextblkno,
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hasho_bucket, hasho_flag, hasho_page_id FROM
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hash_page_stats(get_raw_page('test_hash_a_idx', 0));
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ERROR: page is not a hash bucket or overflow page
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SELECT live_items, dead_items, page_size, hasho_prevblkno, hasho_nextblkno,
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hasho_bucket, hasho_flag, hasho_page_id FROM
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hash_page_stats(get_raw_page('test_hash_a_idx', 1));
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-[ RECORD 1 ]---+-----------
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live_items | 0
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dead_items | 0
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page_size | 8192
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hasho_prevblkno | 3
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hasho_nextblkno | 4294967295
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hasho_bucket | 0
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hasho_flag | 2
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hasho_page_id | 65408
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SELECT live_items, dead_items, page_size, hasho_prevblkno, hasho_nextblkno,
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hasho_bucket, hasho_flag, hasho_page_id FROM
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hash_page_stats(get_raw_page('test_hash_a_idx', 2));
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-[ RECORD 1 ]---+-----------
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live_items | 0
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dead_items | 0
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page_size | 8192
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hasho_prevblkno | 3
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hasho_nextblkno | 4294967295
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hasho_bucket | 1
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hasho_flag | 2
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hasho_page_id | 65408
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SELECT live_items, dead_items, page_size, hasho_prevblkno, hasho_nextblkno,
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hasho_bucket, hasho_flag, hasho_page_id FROM
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hash_page_stats(get_raw_page('test_hash_a_idx', 3));
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-[ RECORD 1 ]---+-----------
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live_items | 1
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dead_items | 0
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page_size | 8192
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hasho_prevblkno | 3
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hasho_nextblkno | 4294967295
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hasho_bucket | 2
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hasho_flag | 2
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hasho_page_id | 65408
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SELECT live_items, dead_items, page_size, hasho_prevblkno, hasho_nextblkno,
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hasho_bucket, hasho_flag, hasho_page_id FROM
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hash_page_stats(get_raw_page('test_hash_a_idx', 4));
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-[ RECORD 1 ]---+-----------
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live_items | 0
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dead_items | 0
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page_size | 8192
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hasho_prevblkno | 3
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hasho_nextblkno | 4294967295
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hasho_bucket | 3
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hasho_flag | 2
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hasho_page_id | 65408
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SELECT live_items, dead_items, page_size, hasho_prevblkno, hasho_nextblkno,
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hasho_bucket, hasho_flag, hasho_page_id FROM
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hash_page_stats(get_raw_page('test_hash_a_idx', 5));
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ERROR: page is not a hash bucket or overflow page
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SELECT * FROM hash_page_items(get_raw_page('test_hash_a_idx', 0));
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ERROR: page is not a hash bucket or overflow page
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SELECT * FROM hash_page_items(get_raw_page('test_hash_a_idx', 1));
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(0 rows)
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SELECT * FROM hash_page_items(get_raw_page('test_hash_a_idx', 2));
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(0 rows)
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SELECT * FROM hash_page_items(get_raw_page('test_hash_a_idx', 3));
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-[ RECORD 1 ]----------
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itemoffset | 1
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ctid | (0,1)
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data | 2389907270
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SELECT * FROM hash_page_items(get_raw_page('test_hash_a_idx', 4));
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(0 rows)
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SELECT * FROM hash_page_items(get_raw_page('test_hash_a_idx', 5));
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ERROR: page is not a hash bucket or overflow page
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DROP TABLE test_hash;
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