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Comment:More documentation on how PRAGMA index_info and PRAGMA index_xinfo handle indexes on expressions.
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SHA3-256: d9d337b9270d984f8f46cb8ac403975c75de2c217fb99bef6bdfec94f8206cad
User & Date: drh 2019-09-26 19:24:07.687
Context
2019-09-26
19:34
Update the RBU documentation to remove the constraint about it not working with indexes on expressions. (check-in: e7771db6cc user: drh tags: trunk)
19:24
More documentation on how PRAGMA index_info and PRAGMA index_xinfo handle indexes on expressions. (check-in: d9d337b927 user: drh tags: trunk)
19:02
Fix introspection pragma documentation to show that they are now on by default. Add documentation for the TCL Interface config method. (check-in: a94ea31acb user: drh tags: trunk)
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    index-columns are not shown by the index_info pragma, but they are
    listed by the [index_xinfo pragma].</p>

    <p>Output columns from the index_info pragma are as follows:
    <ol>
    <li>^(The rank of the column within the index.  (0 means left-most.))^
    <li>^The rank of the column within the table being indexed.
        ^A value of -1 means [rowid] and a value of -2 means that an
        [expression index|expression] is being used.
    <li>^The name of the column being indexed.
    <li>^The name of the column being indexed.  ^This columns is NULL
        if the column is the [rowid] or an [expression index|expression].
    </ol>

    <p>If there is no index named <i>index-name</i> but there is a
    [WITHOUT ROWID] table with that name, then (as of
    SQLite [version 3.30.0] on [dateof:3.30.0]) this pragma returns the
    PRIMARY KEY columns of the WITHOUT ROWID table as they are used
    in the records of the underlying b-tree, which is to say with
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    locate the table entry that corresponds to each index entry.)

    <p>Output columns from the index_xinfo pragma are as follows:
    <ol>
    <li>^(The rank of the column within the index. (0 means left-most.
         Key columns come before auxiliary columns.))^
    <li>^The rank of the column within the table being indexed, or -1 if
         the index-column is the [rowid] of the table being indexed.
         the index-column is the [rowid] of the table being indexed and -2
         if the [expression index|index is on an expression].
    <li>^The name of the column being indexed, or NULL if the index-column
         is the [rowid] of the table being indexed.
         is the [rowid] of the table being indexed or an
         [expression index|expression].
    <li>^1 if the index-column is sorted in reverse (DESC) order by the
         index and 0 otherwise.
    <li>^The name for the [collating sequence]
         used to compare values in the index-column.
    <li>^1 if the index-column is a key column and 0 if the index-column
         is an auxiliary column.
    </ol>
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