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Diffstat (limited to 'src/third_party/wiredtiger/src/docs/tune-read-only.dox')
| -rw-r--r-- | src/third_party/wiredtiger/src/docs/tune-read-only.dox | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/src/third_party/wiredtiger/src/docs/tune-read-only.dox b/src/third_party/wiredtiger/src/docs/tune-read-only.dox new file mode 100644 index 00000000000..98db7e0782e --- /dev/null +++ b/src/third_party/wiredtiger/src/docs/tune-read-only.dox @@ -0,0 +1,26 @@ +/*! @page tune_read_only Read-only objects + +Cursors opened on checkpoints (either named, or using the special "last +checkpoint" name "WiredTigerCheckpoint") are read-only objects. Unless +memory mapping is configured off (using the "mmap" configuration string +to ::wiredtiger_open), read-only objects are mapped into process memory +instead of being read through the WiredTiger cache. Using read-only +objects where possible minimizes the amount of buffer cache memory +required by WiredTiger applications and the work required for buffer +cache management, as well as reducing the number of memory copies from +the operating system buffer cache into application memory. + +To open a named checkpoint, use the configuration string "checkpoint" +to the WT_SESSION::open_cursor method: +@snippet ex_all.c open a named checkpoint + +To open the last checkpoint taken in the object, use the configuration +string "checkpoint" with the name "WiredTigerCheckpoint" to the +WT_SESSION::open_cursor method: +@snippet ex_all.c open the default checkpoint + +Reading from checkpoints is only supported on row- and column-store +objects, LSM cursors cannot be opened with a non-empty \c "checkpoint" +configuration. + + */ |