SQLite Release 3.12.1 On 2016-04-08

• Fix a boundary condition error introduced by version 3.12.0 that can result in a crash during heavy SAVEPOINT usage. Ticket 7f7f8026eda38.
• Fix views so that they inherit column datatypes from the table that they are defined against, when possible.
• Fix the query planner so that IS and IS NULL operators are able to drive an index on a LEFT OUTER JOIN.

  Hashes:

• SQLITE_SOURCE_ID: "2016-04-08 15:09:49 fe7d3b75fe1bde41511b323925af8ae1b910bc4d"
• SHA1 for sqlite3.c: ebb18593350779850e3e1a930eb84a70fca8c1d1

Changes carried forward from version 3.12.0 (2016-03-29):

Potentially Disruptive Change:

• The SQLITE_DEFAULT_PAGE_SIZE is increased from 1024 to 4096. The SQLITE_DEFAULT_CACHE_SIZE is changed from 2000 to -2000 so the same amount of cache memory is used by default. See the application note on the version 3.12.0 page size change for further information.

  Performance enhancements:

• Enhancements to the Lemon parser generator so that it creates a smaller and faster SQL parser.
• Only create master journal files if two or more attached databases are all modified, do not have PRAGMA synchronous set to OFF, and do not have the journal_mode set to OFF, MEMORY, or WAL.
• Only create statement journal files when their size exceeds a threshold. Otherwise the journal is held in memory and no I/O occurs. The threshold can be configured at compile-time using SQLITE_STMTJRNL_SPILL or at start-time using sqlite3_config(SQLITE_CONFIG_STMTJRNL_SPILL).
• The query planner is able to optimize IN operators on virtual tables even if the xBestIndex method does not set the sqlite3_index_constraint_usage.omit flag of the virtual table column to the left of the IN operator.
• The query planner now does a better job of optimizing virtual table accesses in a 3-way or higher join where constraints on the virtual table are split across two or more other tables of the join.
• More efficient handling of application-defined SQL functions, especially in cases where the application defines hundreds or thousands of custom functions.
• The query planner considers the LIMIT clause when estimating the cost of ORDER BY.
• The configure script (on unix) automatically detects pread() and pwrite() and sets compile-time options to use those OS interfaces if they are available.
• Reduce the amount of memory needed to hold the schema.
• Other miscellaneous micro-optimizations for improved performance and reduced memory usage.

  New Features:

• Added the SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER option to sqlite3_db_config() which allows the two-argument version of the fts3_tokenizer() SQL function to be enabled or disabled at run-time.
• Added the sqlite3rbu_bp_progress() interface to the RBU extension.
• The PRAGMA defer_foreign_keys=ON statement now also disables RESTRICT actions on foreign key.
• Added the sqlite3_system_errno() interface.
• Added the SQLITE_DEFAULT_SYNCHRONOUS and SQLITE_DEFAULT_WAL_SYNCHRONOUS compile-time options. The SQLITE_DEFAULT_SYNCHRONOUS compile-time option replaces the SQLITE_EXTRA_DURABLE option, which is no longer supported.
• Enhanced the ".stats" command in the command-line shell to show more information about I/O performance obtained from /proc, when available.

  Bug fixes:

• Make sure the sqlite3_set_auxdata() values from multiple triggers within a single statement do not interfere with one another. Ticket dc9b1c91.
• Fix the code generator for expressions of the form "x IN (SELECT...)" where the SELECT statement on the RHS is a correlated subquery. Ticket 5e3c886796e5512e.
• Fix a harmless TSAN warning associated with the sqlite3_db_readonly() interface.

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