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Overview
| Comment: | Enhancements to the comments on sqlite3FindInIndex(). No code changes. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: | b1a4c394995eb90b3fb43ab204704bda03799303 |
| User & Date: | drh 2012-09-18 17:08:33 |
Context
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2012-09-18
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| 19:29 | Enhance IN processing to allow efficient use of indices with numeric affinities. Add test cases for IN processing that would have spotted the error in the [2be661a48023f4] check-in. check-in: 5ded9b68 user: drh tags: trunk | |
| 17:32 | This change generates incorrect code when there are two or more IN operators in the WHERE clause that are both used by the same index. Was: Omit an unnecessary OP_IfNull that immediately follows an OP_Rowid. Closed-Leaf check-in: 2be661a4 user: drh tags: mistake | |
| 17:08 | Enhancements to the comments on sqlite3FindInIndex(). No code changes. check-in: b1a4c394 user: drh tags: trunk | |
| 14:00 | Add the stack_usage.tcl script for analyzing the output of objdump on the amalgamation and estimating the sizes of stack frames on each function. check-in: 030013ff user: drh tags: trunk | |
Changes
Changes to src/expr.c.
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int sqlite3CodeOnce(Parse *pParse){
Vdbe *v = sqlite3GetVdbe(pParse); /* Virtual machine being coded */
return sqlite3VdbeAddOp1(v, OP_Once, pParse->nOnce++);
}
/*
** This function is used by the implementation of the IN (...) operator.
** It's job is to find or create a b-tree structure that may be used
** either to test for membership of the (...) set or to iterate through
** its members, skipping duplicates.
**
** The index of the cursor opened on the b-tree (database table, database index
** or ephermal table) is stored in pX->iTable before this function returns.
** The returned value of this function indicates the b-tree type, as follows:
**
** IN_INDEX_ROWID - The cursor was opened on a database table.
** IN_INDEX_INDEX - The cursor was opened on a database index.
** IN_INDEX_EPH - The cursor was opened on a specially created and
** populated epheremal table.
**
** An existing b-tree may only be used if the SELECT is of the simple
** form:
**
** SELECT <column> FROM <table>
**
** If the prNotFound parameter is 0, then the b-tree will be used to iterate
** through the set members, skipping any duplicates. In this case an
** epheremal table must be used unless the selected <column> is guaranteed
** to be unique - either because it is an INTEGER PRIMARY KEY or it
** has a UNIQUE constraint or UNIQUE index.
**
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int sqlite3CodeOnce(Parse *pParse){
Vdbe *v = sqlite3GetVdbe(pParse); /* Virtual machine being coded */
return sqlite3VdbeAddOp1(v, OP_Once, pParse->nOnce++);
}
/*
** This function is used by the implementation of the IN (...) operator.
** The pX parameter is the expression on the RHS of the IN operator, which
** might be either a list of expressions or a subquery.
**
** The job of this routine is to find or create a b-tree object that can
** be used either to test for membership in the RHS set or to iterate through
** all members of the RHS set, skipping duplicates.
**
** A cursor is opened on the b-tree object that the RHS of the IN operator
** and pX->iTable is set to the index of that cursor.
**
** The returned value of this function indicates the b-tree type, as follows:
**
** IN_INDEX_ROWID - The cursor was opened on a database table.
** IN_INDEX_INDEX - The cursor was opened on a database index.
** IN_INDEX_EPH - The cursor was opened on a specially created and
** populated epheremal table.
**
** An existing b-tree might be used if the RHS expression pX is a simple
** subquery such as:
**
** SELECT <column> FROM <table>
**
** If the RHS of the IN operator is a list or a more complex subquery, then
** an ephemeral table might need to be generated from the RHS and then
** pX->iTable made to point to the ephermeral table instead of an
** existing table.
**
** If the prNotFound parameter is 0, then the b-tree will be used to iterate
** through the set members, skipping any duplicates. In this case an
** epheremal table must be used unless the selected <column> is guaranteed
** to be unique - either because it is an INTEGER PRIMARY KEY or it
** has a UNIQUE constraint or UNIQUE index.
**
|