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Overview
| Comment: | Clarification of the meaning of the stat column in sqlite_stat1. |
|---|---|
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: | 83b2bf0c4d3811e788aa22fa2fb2d0b2 |
| User & Date: | drh 2013-09-19 14:30:37 |
Context
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2013-09-30
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| 12:10 | Fix to the releaselog/current.html generator. check-in: e7d9c2101a user: drh tags: trunk | |
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2013-09-19
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| 14:30 | Clarification of the meaning of the stat column in sqlite_stat1. check-in: 83b2bf0c4d user: drh tags: trunk | |
| 14:24 | Leave unspecified what it means for the sqlite_stat3 and sqlite_stat4 tables to have idx columns equal to their tbl column. check-in: c538b41b91 user: drh tags: trunk | |
Changes
Changes to pages/fileformat2.in.
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</pre></blockquote> <p>There is normally one row per index, with the index identified by the name in the sqlite_stat1.idx column. The sqlite_stat1.tbl column is the name of the table to which the index belongs. In each such row, the sqlite_stat.stat column will be a string consisting of a list of integers. The first integer in this list is the number of rows in the index and in the table. The second integer is the average number of rows in the index that have the same value in the first column of the index. The third integer is the average number of rows in the index that have the same value for the first two columns. The N-th integer (for N>1) is the average number of rows in the index which have the same value for the first N-1 columns. For a K-column index, there will be K+1 integers in the stat column. If the index is unique, then the last integer will be 1. <p>The list of integers in the stat column can optionally be followed by the keyword "unordered". The "unordered" keyword, if it is present, must be separated from the last integer by a single space. If the "unordered" keyword is present, then the query planner assumes that the index is unordered and will not use the index for a range query. <p>If the sqlite_stat1.idx column is NULL, then the sqlite_stat1.stat column contains a single integer which is the (estimated) number of rows in the table identified by sqlite_stat1.tbl. <tcl>hd_fragment stat2tab {sqlite_stat2}</tcl> <h4>2.5.4 The sqlite_stat2 table</h4> <p>The sqlite_stat2 is only created and is only used if SQLite is compiled with SQLITE_ENABLE_STAT2 and if the SQLite version number is between |
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</pre></blockquote> <p>There is normally one row per index, with the index identified by the name in the sqlite_stat1.idx column. The sqlite_stat1.tbl column is the name of the table to which the index belongs. In each such row, the sqlite_stat.stat column will be a string consisting of a list of integers. The first integer in this list is the approximate number of rows in the index and in the table. The second integer is the approximate average number of rows in the index that have the same value in the first column of the index. The third integer is the approximate average number of rows in the index that have the same value for the first two columns. The N-th integer (for N>1) is the approximate average number of rows in the index which have the same value for the first N-1 columns. For a K-column index, there will be K+1 integers in the stat column. If the index is unique, then the last integer will be 1. <p>The list of integers in the stat column can optionally be followed by the keyword "unordered". The "unordered" keyword, if it is present, must be separated from the last integer by a single space. If the "unordered" keyword is present, then the query planner assumes that the index is unordered and will not use the index for a range query or for sorting. <p>If the sqlite_stat1.idx column is NULL, then the sqlite_stat1.stat column contains a single integer which is the approximate number of rows in the table identified by sqlite_stat1.tbl. <tcl>hd_fragment stat2tab {sqlite_stat2}</tcl> <h4>2.5.4 The sqlite_stat2 table</h4> <p>The sqlite_stat2 is only created and is only used if SQLite is compiled with SQLITE_ENABLE_STAT2 and if the SQLite version number is between |