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Improvements and simplifications to the equality seek logic. Tests are

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adjusted so that they all pass now.

FossilOrigin-Name: 997ce6c90b454c03cc2ef6934752ee8dd2e520e3
This commit is contained in:
drh
2015-11-05 22:30:54 +00:00
parent 70528d7868
commit b1d607de25
10 changed files with 84 additions and 63 deletions
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32
src/sqliteInt.h
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@@ -1812,9 +1812,8 @@ struct KeyInfo {
};
/*
** An instance of the following structure holds information about a
** single index record that has already been parsed out into individual
** values.
** This object holds a record which has been parsed out into individual
** fields, for the purposes of doing a comparison.
**
** A record is an object that contains one or more fields of data.
** Records are used to store the content of a table row and to store
@@ -1822,11 +1821,30 @@ struct KeyInfo {
** the OP_MakeRecord opcode of the VDBE and is disassembled by the
** OP_Column opcode.
**
** This structure holds a record that has already been disassembled
** into its constituent fields.
** An instance of this object serves as a "key" for doing a search on
** an index b+tree. The goal of the search is to find the entry that
** is closed to the key described by this object. This object might hold
** just a prefix of the key. The number of fields is given by
** pKeyInfo->nField.
**
** The r1 and r2 member variables are only used by the optimized comparison
** functions vdbeRecordCompareInt() and vdbeRecordCompareString().
** The r1 and r2 fields are the values to return if this key is less than
** or greater than a key in the btree, respectively. These are normally
** -1 and +1 respectively, but might be inverted to +1 and -1 if the b-tree
** is in DESC order.
**
** The key comparison functions actually return default_rc when they find
** an equals comparison. default_rc can be -1, 0, or +1. If there are
** multiple entries in the b-tree with the same key (when only looking
** at the first pKeyInfo->nFields,) then default_rc can be set to -1 to
** cause the search to find the last match, or +1 to cause the search to
** find the first match.
**
** The key comparison functions will set eqSeen to true if they ever
** get and equal results when comparing this structure to a b-tree record.
** When default_rc!=0, the search might end up on the record immediately
** before the first match or immediately after the last match. The
** eqSeen field will indicate whether or not an exact match exists in the
** b-tree.
*/
struct UnpackedRecord {
KeyInfo *pKeyInfo; /* Collation and sort-order information */