SQLite version 3.8.1 is now available on the SQLite website: http://www.sqlite.org/ http://sqlite.org/releaselog/3_8_1.html
SQLite version 3.8.1 is a regularly scheduled maintenance release. Upgrading from the previous release is optional, though you should upgrade if you are using partial indices as there was a bug related to partial indices in the previous release that could result in an incorrect answer for count(*) queries. The next generation query planner that was premiered in the previous release continues to work well. The new query planner has been tweaked slightly in the current release to help it make better decisions in some cases, but is largely unchanged. Two new SQL functions, likelihood() and unlikely(), have been added to allow developers to give hints to the query planner without forcing the query planner into a particular decision. Version 3.8.1 is the first SQLite release to take into account the estimated size of table and index rows when choosing a query plan. Row size estimates are based on the declared datatypes of columns. For example, a column of type VARCHAR(1000) is assumed to use much more space than a column of type INT. The datatype-based row size estimate can be overridden by appending a term of the form "sz=NNN" (where NNN is the average row size in bytes) to the end of the sqlite_stat1.stat record for a table or index. Currently, row sizes are only used to help the query planner choose between a table or one of its indices when doing a table scan or a count(*) operation, though future releases are likely to use the estimated row size in other contexts as well. The new PRAGMA stats statement can be used to view row size estimates. Version 3.8.1 adds the SQLITE_ENABLE_STAT4 compile-time option. STAT4 is very similar to STAT3 in that it uses samples from indices to try to guess how many rows of the index will be satisfy by WHERE clause constraints. The difference is that STAT4 samples all columns of the index whereas the older STAT3 only sampled the left-most column. Users of STAT3 are encouraged to upgrade to STAT4. Application developers should use STAT3 and STAT4 with caution since both options, by design, violate the query planner stability guarantee, making it more difficult to ensure uniform performance is widely-deployed and mass-produced embedded applications. -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-announce mailing list sqlite-announce@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-announce