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Overview
Comment: | Add documentation for the SQLITE_DIRECT_OVERFLOW_READ compile-time option. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
02ece32458d307dbdfb8999a433fe631 |
User & Date: | drh 2011-10-21 18:36:15.589 |
Context
2011-10-31
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17:20 | Update changes and news in preparation for the 3.7.9 release. (check-in: b78d9767b2 user: drh tags: trunk) | |
2011-10-21
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18:36 | Add documentation for the SQLITE_DIRECT_OVERFLOW_READ compile-time option. (check-in: 02ece32458 user: drh tags: trunk) | |
16:42 | Documentation updates for the round() function. (check-in: 81fe64736e user: drh tags: trunk) | |
Changes
Changes to pages/changes.in.
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50 51 52 53 54 55 56 | to the [sqlite3_db_status()] interface. <li>Removed support for [SQLITE_ENABLE_STAT2], replacing it with the much more capable [SQLITE_ENABLE_STAT3] option. <li>Enhancements to the sqlite3_analyzer utility program, including the --pageinfo and --stats options and support for multiplexed databases. <li>Enhance the [sqlite3_data_count()] interface so that it can be used to determine if SQLITE_DONE has been seen on the prepared statement. | | | | > | 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 | to the [sqlite3_db_status()] interface. <li>Removed support for [SQLITE_ENABLE_STAT2], replacing it with the much more capable [SQLITE_ENABLE_STAT3] option. <li>Enhancements to the sqlite3_analyzer utility program, including the --pageinfo and --stats options and support for multiplexed databases. <li>Enhance the [sqlite3_data_count()] interface so that it can be used to determine if SQLITE_DONE has been seen on the prepared statement. <li>Added the [SQLITE_FCNTL_OVERWRITE] file-control by which the SQLite core indicates to the VFS that the current transaction will overwrite the entire database file. <li>Increase the default [lookaside memory allocator] allocation size from 100 to 128 bytes. <li>Enhanced the query planner so that it can factor terms in and out of OR expressions in the WHERE clause in an effort to find better indices. <li>Added the [SQLITE_DIRECT_OVERFLOW_READ] compile-time option, causing [overflow pages] to be read directly from the database file, bypassing the [page cache]. <li>Remove limits on the magnitude of precision and width value in the format specifiers of the [sqlite3_mprintf()] family of string rendering routines. <li>Fix a bug that prevent [ALTER TABLE | ALTER TABLE ... RENAME] from working on some virtual tables in a database with a UTF16 encoding. <li>Fix a bug in ASCII-to-float conversion that causes slow performance and incorrect results when converting numbers with ridiculously large exponents. |
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Changes to pages/compile.in.
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188 189 190 191 192 193 194 195 196 197 198 199 200 201 | } COMPILE_OPTION {SQLITE_CASE_SENSITIVE_LIKE} { If this option is present, then the built-in [LIKE] operator will be case sensitive. This same effect can be achieved at run-time using the [case_sensitive_like pragma]. } COMPILE_OPTION {SQLITE_HAVE_ISNAN} { If this option is present, then SQLite will use the isnan() function from the system math library. Without this option (the default behavior) SQLite uses its own internal implementation of isnan(). SQLite uses its own internal isnan() implementation by default because of past problems with system isnan() functions. | > > > > > > > > | 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 | } COMPILE_OPTION {SQLITE_CASE_SENSITIVE_LIKE} { If this option is present, then the built-in [LIKE] operator will be case sensitive. This same effect can be achieved at run-time using the [case_sensitive_like pragma]. } COMPILE_OPTION {SQLITE_DIRECT_OVERFLOW_READ} { When this option is present, content contained in [overflow pages] of the database file is read directly from disk, bypassing the [page cache], during read transactions. In applications that do a lot of reads of large BLOBs, this option might improve read performance. } COMPILE_OPTION {SQLITE_HAVE_ISNAN} { If this option is present, then SQLite will use the isnan() function from the system math library. Without this option (the default behavior) SQLite uses its own internal implementation of isnan(). SQLite uses its own internal isnan() implementation by default because of past problems with system isnan() functions. |
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Changes to pages/fileformat2.in.
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734 735 736 737 738 739 740 741 742 743 744 745 746 747 | is on the b-tree page that the record header can usually be accessed without consulting an overflow page. In hindsight, the designers of the SQLite b-tree logic realize that these thresholds could have been made much simpler. However, the computations cannot be changed without resulting in an incompatible file format. And the current computations work well, even if they are a little complex.</p> <h3>1.6 Cell Payload Overflow Pages</h3> <p>^When the payload of a b-tree cell is too large for the b-tree page, the surplus is spilled onto overflow pages. ^Overflow pages form a linked list. ^The first four bytes of each overflow page are a big-endian integer which is the page number of the next page in the chain, or zero for the final page in the chain. ^The fifth byte through the last usable | > | 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 | is on the b-tree page that the record header can usually be accessed without consulting an overflow page. In hindsight, the designers of the SQLite b-tree logic realize that these thresholds could have been made much simpler. However, the computations cannot be changed without resulting in an incompatible file format. And the current computations work well, even if they are a little complex.</p> <tcl>hd_fragment ovflpgs {overflow page} {overflow pages}</tcl> <h3>1.6 Cell Payload Overflow Pages</h3> <p>^When the payload of a b-tree cell is too large for the b-tree page, the surplus is spilled onto overflow pages. ^Overflow pages form a linked list. ^The first four bytes of each overflow page are a big-endian integer which is the page number of the next page in the chain, or zero for the final page in the chain. ^The fifth byte through the last usable |
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