Hello, I have two tables, inodes and inode_blocks, which have indices on id and inode respectively.
The following query seems to make optimal use of the indices: sqlite> explain query plan SELECT 1 from inode_blocks where inode=42 UNION SELECT 1 from inodes where block_id is not null and id=42; 1|0|0|SEARCH TABLE inode_blocks USING COVERING INDEX sqlite_autoindex_inode_blocks_1 (inode=?) (~5 rows) 2|0|0|SEARCH TABLE inodes USING INTEGER PRIMARY KEY (rowid=?) (~1 rows) 0|0|0|COMPOUND SUBQUERIES 1 AND 2 USING TEMP B-TREE (UNION) However, if I use an intermediate view: sqlite>CREATE VIEW inode_blocks_v AS SELECT * FROM inode_blocks UNION SELECT id as inode, 0 as blockno, block_id FROM inodes WHERE block_id IS NOT NULL and then run the same query on the view, SQLite scans through all involved tables: sqlite> explain query plan SELECT 1 FROM inode_blocks_v WHERE inode=42; 2|0|0|SCAN TABLE inode_blocks (~10711 rows) 3|0|0|SCAN TABLE inodes (~131030 rows) 1|0|0|COMPOUND SUBQUERIES 2 AND 3 USING TEMP B-TREE (UNION) 0|0|0|SCAN SUBQUERY 1 (~14174 rows) Is there any way I can make SQLite use the indices here as well? I can't see any reason of why they couldn't be used. Best, -Nikolaus -- »Time flies like an arrow, fruit flies like a Banana.« PGP fingerprint: 5B93 61F8 4EA2 E279 ABF6 02CF A9AD B7F8 AE4E 425C _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users