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Overview
| Comment: | Only use the direct-overflow-read optimization if all data from the overflow page in question is being read. |
|---|---|
| Downloads: | Tarball | ZIP archive |
| Timelines: | family | ancestors | descendants | both | overflow-pgno-cache |
| Files: | files | file ages | folders |
| SHA1: |
d8e1f75ddf10f3c0b21acd5455f90fdc |
| User & Date: | dan 2014-03-20 18:56:35.309 |
Context
|
2014-03-31
| ||
| 22:03 | Merge in the latest changes and fixes from trunk. (check-in: f6211540c9 user: drh tags: overflow-pgno-cache) | |
|
2014-03-20
| ||
| 18:56 | Only use the direct-overflow-read optimization if all data from the overflow page in question is being read. (check-in: d8e1f75ddf user: dan tags: overflow-pgno-cache) | |
|
2014-03-11
| ||
| 23:44 | Remove a stray C99-style comment. (check-in: f500e87d6e user: drh tags: overflow-pgno-cache) | |
Changes
Changes to src/btree.c.
| ︙ | ︙ | |||
3947 3948 3949 3950 3951 3952 3953 3954 3955 3956 3957 3958 3959 3960 3961 3962 3963 3964 3965 3966 3967 3968 3969 |
){
unsigned char *aPayload;
int rc = SQLITE_OK;
u32 nKey;
int iIdx = 0;
MemPage *pPage = pCur->apPage[pCur->iPage]; /* Btree page of current entry */
BtShared *pBt = pCur->pBt; /* Btree this cursor belongs to */
assert( pPage );
assert( pCur->eState==CURSOR_VALID );
assert( pCur->aiIdx[pCur->iPage]<pPage->nCell );
assert( cursorHoldsMutex(pCur) );
getCellInfo(pCur);
aPayload = pCur->info.pCell + pCur->info.nHeader;
nKey = (pPage->intKey ? 0 : (int)pCur->info.nKey);
if( NEVER(offset+amt > nKey+pCur->info.nData)
|| &aPayload[pCur->info.nLocal] > &pPage->aData[pBt->usableSize]
){
/* Trying to read or write past the end of the data is an error */
return SQLITE_CORRUPT_BKPT;
}
| > > | 3947 3948 3949 3950 3951 3952 3953 3954 3955 3956 3957 3958 3959 3960 3961 3962 3963 3964 3965 3966 3967 3968 3969 3970 3971 |
){
unsigned char *aPayload;
int rc = SQLITE_OK;
u32 nKey;
int iIdx = 0;
MemPage *pPage = pCur->apPage[pCur->iPage]; /* Btree page of current entry */
BtShared *pBt = pCur->pBt; /* Btree this cursor belongs to */
int bEnd; /* True if reading to end of data */
assert( pPage );
assert( pCur->eState==CURSOR_VALID );
assert( pCur->aiIdx[pCur->iPage]<pPage->nCell );
assert( cursorHoldsMutex(pCur) );
getCellInfo(pCur);
aPayload = pCur->info.pCell + pCur->info.nHeader;
nKey = (pPage->intKey ? 0 : (int)pCur->info.nKey);
bEnd = (offset+amt==nKey+pCur->info.nData);
if( NEVER(offset+amt > nKey+pCur->info.nData)
|| &aPayload[pCur->info.nLocal] > &pPage->aData[pBt->usableSize]
){
/* Trying to read or write past the end of the data is an error */
return SQLITE_CORRUPT_BKPT;
}
|
| ︙ | ︙ | |||
4060 4061 4062 4063 4064 4065 4066 4067 4068 4069 4070 4071 4072 4073 4074 4075 4076 4077 4078 4079 4080 |
/* If all the following are true:
**
** 1) this is a read operation, and
** 2) data is required from the start of this overflow page, and
** 3) the database is file-backed, and
** 4) there is no open write-transaction, and
** 5) the database is not a WAL database,
**
** then data can be read directly from the database file into the
** output buffer, bypassing the page-cache altogether. This speeds
** up loading large records that span many overflow pages.
*/
if( (eOp&0x01)==0 /* (1) */
&& offset==0 /* (2) */
&& pBt->inTransaction==TRANS_READ /* (4) */
&& (fd = sqlite3PagerFile(pBt->pPager))->pMethods /* (3) */
&& pBt->pPage1->aData[19]==0x01 /* (5) */
){
u8 aSave[4];
u8 *aWrite = &pBuf[-4];
memcpy(aSave, aWrite, 4);
| > > | 4062 4063 4064 4065 4066 4067 4068 4069 4070 4071 4072 4073 4074 4075 4076 4077 4078 4079 4080 4081 4082 4083 4084 |
/* If all the following are true:
**
** 1) this is a read operation, and
** 2) data is required from the start of this overflow page, and
** 3) the database is file-backed, and
** 4) there is no open write-transaction, and
** 5) the database is not a WAL database,
** 6) all data from the page is being read.
**
** then data can be read directly from the database file into the
** output buffer, bypassing the page-cache altogether. This speeds
** up loading large records that span many overflow pages.
*/
if( (eOp&0x01)==0 /* (1) */
&& offset==0 /* (2) */
&& (bEnd || a==ovflSize) /* (6) */
&& pBt->inTransaction==TRANS_READ /* (4) */
&& (fd = sqlite3PagerFile(pBt->pPager))->pMethods /* (3) */
&& pBt->pPage1->aData[19]==0x01 /* (5) */
){
u8 aSave[4];
u8 *aWrite = &pBuf[-4];
memcpy(aSave, aWrite, 4);
|
| ︙ | ︙ |
Changes to test/func.test.
| ︙ | ︙ | |||
1297 1298 1299 1300 1301 1302 1303 |
do_test func-29.3 {
db close
sqlite3 db test.db
sqlite3_db_status db CACHE_MISS 1
db eval {SELECT typeof(+x) FROM t29 ORDER BY id}
} {integer null real blob text}
if {[permutation] != "mmap"} {
| > | | | | | > | 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 |
do_test func-29.3 {
db close
sqlite3 db test.db
sqlite3_db_status db CACHE_MISS 1
db eval {SELECT typeof(+x) FROM t29 ORDER BY id}
} {integer null real blob text}
if {[permutation] != "mmap"} {
ifcapable !direct_read {
do_test func-29.4 {
set x [lindex [sqlite3_db_status db CACHE_MISS 1] 1]
if {$x>100} {set x many}
set x
} {many}
}
}
do_test func-29.5 {
db close
sqlite3 db test.db
sqlite3_db_status db CACHE_MISS 1
db eval {SELECT sum(length(x)) FROM t29}
} {1000009}
|
| ︙ | ︙ |