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fc8219dc54
It did that to verify that the page was an overflow page rather than anything else, but that means that checking the status of all the overflow bits requires reading the entire index. So don't do that. The new code validates that the page is not a primary bucket page or bitmap page by looking at the metapage, so that using this on large numbers of pages can be reasonably efficient. Ashutosh Sharma, per a complaint from me, and with further modifications by me.
164 lines
6.2 KiB
Plaintext
164 lines
6.2 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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WARNING: hash indexes are not WAL-logged and their use is discouraged
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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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