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Overview
| Comment: | Fix typos in the compile.html page. |
|---|---|
| Timelines: | family | ancestors | descendants | both | branch-3.24 |
| Files: | files | file ages | folders |
| SHA3-256: | 10c05df9fb6ec32963b37d75c029748a |
| User & Date: | drh 2018-06-09 22:13:37 |
Context
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2018-06-15
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| 19:12 | Fix missing "const" in the documentation of the argv parameters to the xCreate and xConnect methods in the sqlite3_module object. check-in: 2ee890a53a user: drh tags: branch-3.24 | |
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2018-06-09
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| 22:13 | Fix typos in the compile.html page. check-in: 10c05df9fb user: drh tags: branch-3.24 | |
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2018-06-05
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| 23:20 | Clarification that the overwrite optimization does not affect the behavior of triggers. check-in: 27b8057665 user: drh tags: branch-3.24 | |
Changes
Changes to pages/compile.in.
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The default sorting procedure is to gather all information that will ultimately be output into a "record" and pass that complete record to the sorter. But in some cases, for example if some of the output columns consists of large BLOB values, the size of the each record can be large, which means that the sorter has to either use more memory, and/or write more content to temporary storage. <p> When SQLITE_ENABLE_SORTER_PREFERENCES is enabled, the records passed to the sorter often contain only a [ROWID] value. Such records are much smaller. This means the sorter has much less "payload" to deal with and can run faster. After sorting has occurred, the ROWID is used to look up the output column values in the original table. That requires another search into the table, and could potentially result in a slowdown. Or, it might be a performance win, depending on how large the values are. <p> Even when the SQLITE_ENABLE_SORTER_PREFERENCES compile-time option is on, sorter references are still disabled by default. To use sorter references, the application must set a sorter reference size threshold using the [sqlite3_config]([SQLITE_CONFIG_SORTERREF_SIZE]) interface at start-time. <p> Because the SQLite developers do not know whether the SQLITE_ENABLE_SORTER_PERFERENCES option will help or hurt performance, it is disabled by default at this time (2018-05-04). It might be enabled by default in some future release, depending on what is learned about its inpact on performance. } COMPILE_OPTION {SQLITE_ENABLE_STMT_SCANSTATUS} { This option enables the [sqlite3_stmt_scanstatus()] interface. The [sqlite3_stmt_scanstatus()] interface is normally omitted from the build because it imposes a small performance penalty, even on statements that do not use the feature. |
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The default sorting procedure is to gather all information that will ultimately be output into a "record" and pass that complete record to the sorter. But in some cases, for example if some of the output columns consists of large BLOB values, the size of the each record can be large, which means that the sorter has to either use more memory, and/or write more content to temporary storage. <p> When SQLITE_ENABLE_SORTER_REFERENCES is enabled, the records passed to the sorter often contain only a [ROWID] value. Such records are much smaller. This means the sorter has much less "payload" to deal with and can run faster. After sorting has occurred, the ROWID is used to look up the output column values in the original table. That requires another search into the table, and could potentially result in a slowdown. Or, it might be a performance win, depending on how large the values are. <p> Even when the SQLITE_ENABLE_SORTER_REFERENCES compile-time option is on, sorter references are still disabled by default. To use sorter references, the application must set a sorter reference size threshold using the [sqlite3_config]([SQLITE_CONFIG_SORTERREF_SIZE]) interface at start-time. <p> Because the SQLite developers do not know whether the SQLITE_ENABLE_SORTER_REFERENCES option will help or hurt performance, it is disabled by default at this time (2018-05-04). It might be enabled by default in some future release, depending on what is learned about its impact on performance. } COMPILE_OPTION {SQLITE_ENABLE_STMT_SCANSTATUS} { This option enables the [sqlite3_stmt_scanstatus()] interface. The [sqlite3_stmt_scanstatus()] interface is normally omitted from the build because it imposes a small performance penalty, even on statements that do not use the feature. |