Alessandro Bonazzi 5c7aa8c1c0 Patch level : 12.0 no-patch
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Aggiunta documentazione di sqlite 3
2020-11-29 00:32:36 +01:00

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<h2>SQLite Release 3.21.0 On 2017-10-24</h2><p><ol class='lessindent'>
<li> Take advantage of the atomic-write capabilities in the
<a href="https://en.wikipedia.org/wiki/F2FS">F2FS filesystem</a> when available, for
greatly reduced transaction overhead. This currently requires the
<a href="../compile.html#enable_batch_atomic_write">SQLITE_ENABLE_BATCH_ATOMIC_WRITE</a> compile-time option.
<li> Allow <a href="../lang_attach.html">ATTACH</a> and <a href="../lang_detach.html">DETACH</a> commands to work inside of a transaction.
<li> Allow <a href="../vtab.html#worid">WITHOUT ROWID virtual tables</a> to be writable if the PRIMARY KEY
contains exactly one column.
<li> The "fsync()" that occurs after the header is written in a WAL reset
now uses the sync settings for checkpoints. This means it will use a
"fullfsync" on macs if <a href="../pragma.html#pragma_checkpoint_fullfsync">PRAGMA checkpoint_fullfsync</a> set on.
<li> The <a href="../c3ref/libversion.html">sqlite3_sourceid()</a> function tries to detect if the source code has
been modified from what is checked into version control and if there are
modifications, the last four characters of the version hash are shown as
"alt1" or "alt2". The objective is to detect accidental and/or careless
edits. A forger can subvert this feature.
<li> Improved de-quoting of column names for <a href="../lang_createtable.html#createtabas">CREATE TABLE AS</a> statements with
an aggregate query on the right-hand side.
<li> Fewer "stat()" system calls issued by the unix VFS.
<li> Enhanced the <a href="../optoverview.html#like_opt">LIKE optimization</a> so that it works with an <a href="../lang_expr.html#like">ESCAPE</a> clause.
<li> Enhanced <a href="../pragma.html#pragma_integrity_check">PRAGMA integrity_check</a> and <a href="../pragma.html#pragma_quick_check">PRAGMA quick_check</a> to detect obscure
row corruption that they were formerly missing. Also update both pragmas
so that they return error text rather than SQLITE_CORRUPT when encountering
corruption in <a href="../fileformat2.html#record_format">records</a>.
<li> The query planner now prefers to implement FROM-clause subqueries using
<a href="../optoverview.html#coroutines">co-routines</a> rather using the <a href="../optoverview.html#flattening">query flattener</a> optimization. Support for
the use of co-routines for subqueries may no longer be disabled.
<li> Pass information about !=, IS, IS NOT, NOT NULL, and IS NULL constraints
into the <a href="../vtab.html#xbestindex">xBestIndex</a> method of virtual tables.
<li> Enhanced the <a href="../csv.html">CSV virtual table</a> so that it accepts the last row of
input if the final new-line character is missing.
<li> Remove the rarely-used "scratch" memory allocator. Replace it with the
<a href="../c3ref/c_config_covering_index_scan.html#sqliteconfigsmallmalloc">SQLITE_CONFIG_SMALL_MALLOC</a> configuration setting that gives SQLite
a hint that large memory allocations should be avoided when possible.
<li> Added the
<a href="https://sqlite.org/src/file/ext/misc/unionvtab.c">swarm virtual table</a>
to the existing union virtual table extension.
<li> Added the
<a href="https://sqlite.org/src/file/src/dbpage.c">sqlite_dbpage virtual table</a>
for providing direct access to pages
of the database file. The source code is built into the <a href="../amalgamation.html">amalgamation</a> and
is activated using the <a href="../compile.html#enable_dbpage_vtab">-DSQLITE_ENABLE_DBPAGE_VTAB</a> compile-time option.
<li> Add a new type of fts5vocab virtual table - "instance" - that provides
direct access to an FTS5 full-text index at the lowest possible level.
<li> Remove a call to rand_s() in the Windows VFS since it was causing problems
in Firefox on some older laptops.
<li> The <a href="https://sqlite.org/src/finfo?name=src/shell.c">src/shell.c</a> source code
to the <a href="../cli.html">command-line shell</a> is no longer under version control. That file
is now generated as part of the build process.
<li> Miscellaneous <a href="../cpu.html#microopt">microoptimizations</a> reduce CPU usage by about 2.1%.
<li> Bug fixes:
<ol type="a">
<li> Fix a faulty assert() statement discovered by OSSFuzz.
Ticket <a href="https://sqlite.org/src/info/cb91bf4290c211d">cb91bf4290c211d</a>
<li> Fix an obscure memory leak in <a href="../c3ref/result_blob.html">sqlite3_result_pointer()</a>.
Ticket <a href="https://sqlite.org/src/info/7486aa54b968e9b">7486aa54b968e9b</a>
<li> Avoid a possible use-after-free error by deferring schema resets until
after the query planner has finished running.
Ticket <a href="https://sqlite.org/src/info/be436a7f4587ce5">be436a7f4587ce5</a>
<li> Only use indexes-on-expressions to optimize ORDER BY or GROUP BY if
the COLLATE is correct.
Ticket <a href="https://sqlite.org/src/info/e20dd54ab0e4383">e20dd54ab0e4383</a>
<li> Fix an assertion fault that was coming up when the expression in an
index-on-expressions is really a constant.
Ticket <a href="https://sqlite.org/src/info/aa98619ad08ddca">aa98619ad08ddca</a>
<li> Fix an assertion fault that could occur following
<a href="../pragma.html#pragma_reverse_unordered_selects">PRAGMA reverse_unordered_selects</a>.
Ticket <a href="https://sqlite.org/src/info/cb91bf4290c211d">cb91bf4290c211d</a>
<li> Fix a segfault that can occur for queries that use table-valued functions
in an IN or EXISTS subquery.
Ticket <a href="https://sqlite.org/src/info/b899b6042f97f5">b899b6042f97f5</a>
<li> Fix a potential integer overflow problem when compiling a particular
horrendous common table expression. This was another problem discovered
by OSSFuzz. Check-in <a href="https://sqlite.org/src/info/6ee8cb6ae5">6ee8cb6ae5</a>.
<li> Fix a potential out-of-bound read when querying a corrupt database file,
a problem detected by Natalie Silvanovich of Google Project Zero.
Check-in <a href="https://sqlite.org/src/info/04925dee41a21f">04925dee41a21f</a>.
</ol>
<p><b>Hashes:</b>
<li>SQLITE_SOURCE_ID: "2017-10-24 18:55:49 1a584e499906b5c87ec7d43d4abce641fdf017c42125b083109bc77c4de48827"
<li>SHA3-256 for sqlite3.c: 84c181c0283d0320f488357fc8aab51898370c157601459ebee49d779036fe03
</ol></p>
<p>A <a href="../changes.html">complete list of SQLite releases</a>
in a single page and a <a href="../chronology.html">chronology</a> are both also available.
A detailed history of every
check-in is available at
<a href="http://www.sqlite.org/src/timeline">
SQLite version control site</a>.</p>