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Diffstat (limited to 'src/third_party/wiredtiger/src/docs/tune-file-alloc.dox')
| -rw-r--r-- | src/third_party/wiredtiger/src/docs/tune-file-alloc.dox | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/src/third_party/wiredtiger/src/docs/tune-file-alloc.dox b/src/third_party/wiredtiger/src/docs/tune-file-alloc.dox new file mode 100644 index 00000000000..062a0170ac8 --- /dev/null +++ b/src/third_party/wiredtiger/src/docs/tune-file-alloc.dox @@ -0,0 +1,30 @@ +/*! @page tune_file_alloc File allocation + +@section tuning_system_file_block_grow File growth + +It's faster on some filesystems to grow a file in chunks rather than to +extend it a block at a time as new blocks are written. By configuring +the wiredtiger_open functions \c file_extend value, applications can +grow files ahead of the blocks being written. + +@snippet ex_all.c Configure file_extend + +The system calls used to extend files in chunks on some systems require +locking across the system call, which may decrease performance. Before +configuring a \c file_extend value, before and after throughput should +be carefully evaluated. + +@section tuning_system_file_block_allocation File block allocation + +By default, when file blocks are being reused, WiredTiger attempts to +avoid file fragmentation by selecting the smallest available block +rather than splitting a larger available block into two. The \c +block_allocation configuration string to WT_SESSION::create can be set +to \c first to change the algorithm to first-fit, that is, take the +first available block in the file. Applications where file size is more +of an issue than file fragmentation (for example, applications with +fixed-size blocks) might want to configure this way. + +@snippet ex_all.c Configure block_allocation + + */ |