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Activate the cell-overwrite optimization for index b-trees.

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FossilOrigin-Name: a68697d10ef17d452c8279181186faad7bc54e3a35858a336552f717449065ea
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drh
2018-05-07 18:41:19 +00:00
parent d720d394d0
commit 89ee229810
4 changed files with 42 additions and 11 deletions
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21
src/btree.h
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@@ -259,13 +259,28 @@ int sqlite3BtreeDelete(BtCursor*, u8 flags);
** entry in either an index or table btree.
**
** Index btrees (used for indexes and also WITHOUT ROWID tables) contain
** an arbitrary key and no data. These btrees have pKey,nKey set to their
** key and pData,nData,nZero set to zero.
** an arbitrary key and no data. These btrees have pKey,nKey set to the
** key and the pData,nData,nZero fields are uninitialized. The aMem,nMem
** fields give an array of Mem objects that are a decomposition of the key.
** The nMem field might be zero, indicating that no decomposition is available.
**
** Table btrees (used for rowid tables) contain an integer rowid used as
** the key and passed in the nKey field. The pKey field is zero.
** pData,nData hold the content of the new entry. nZero extra zero bytes
** are appended to the end of the content when constructing the entry.
** The aMem,nMem fields are uninitialized for table btrees.
**
** Field usage summary:
**
** Table BTrees Index Btrees
**
** pKey always NULL encoded key
** nKey the ROWID length of pKey
** pData data not used
** aMem not used decomposed key value
** nMem not used entries in aMem
** nData length of pData not used
** nZero extra zeros after pData not used
**
** This object is used to pass information into sqlite3BtreeInsert(). The
** same information used to be passed as five separate parameters. But placing
@@ -276,7 +291,7 @@ int sqlite3BtreeDelete(BtCursor*, u8 flags);
struct BtreePayload {
const void *pKey; /* Key content for indexes. NULL for tables */
sqlite3_int64 nKey; /* Size of pKey for indexes. PRIMARY KEY for tabs */
const void *pData; /* Data for tables. NULL for indexes */
const void *pData; /* Data for tables. */
sqlite3_value *aMem; /* First of nMem value in the unpacked pKey */
u16 nMem; /* Number of aMem[] value. Might be zero */
int nData; /* Size of pData. 0 if none. */