Details
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Bug
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Status: On Hold
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Medium
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Resolution: Unresolved
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8.0.13-4, 5.7.25-28, Not 5.6.x
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None
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None
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Same pt-summary and pt-mysql-summary as other created tickets. Example can be found here...
Description
I have altered the rocksdb_default_cf_options variable to include a setting for MIN_WRITE_BUFFER_NUMBER_TO_MERGE for my test column family. Per the documentation found here...
https://github.com/facebook/rocksdb/wiki/RocksDB-Tuning-Guide#flushing-options
I should be able to create multiple memtables prior to a flush, however this doesn't appear to be the case.
As you can see below I set the value to 4. I started loading data into my column family and you can see from the output of information_schema.ROCKSDB_CFSTATS I never got more than one immutable memtable.
mysql> select * from information_schema.ROCKSDB_CF_OPTIONS cfo where cfo.CF_NAME = 'cf_t1' and cfo.OPTION_TYPE IN ('MIN_WRITE_BUFFER_NUMBER_TO_MERGE', 'WRITE_BUFFER_SIZE'); +---------+----------------------------------+-----------+ | CF_NAME | OPTION_TYPE | VALUE | +---------+----------------------------------+-----------+ | cf_t1 | WRITE_BUFFER_SIZE | 100663296 | | cf_t1 | MIN_WRITE_BUFFER_NUMBER_TO_MERGE | 4 | +---------+----------------------------------+-----------+ 2 rows in set (0.01 sec) mysql> select * from information_schema.ROCKSDB_CF_OPTIONS cfo where cfo.CF_NAME = 'cf_t1' and cfo.OPTION_TYPE IN ('MIN_WRITE_BUFFER_NUMBER_TO_MERGE', 'WRITE_BUFFER_SIZE'); +---------+----------------------------------+----------+ | CF_NAME | OPTION_TYPE | VALUE | +---------+----------------------------------+----------+ | cf_t1 | WRITE_BUFFER_SIZE | 33554432 | | cf_t1 | MIN_WRITE_BUFFER_NUMBER_TO_MERGE | 4 | +---------+----------------------------------+----------+ 2 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+-------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+-------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 800 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 800 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 0 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+-------+ 9 rows in set (0.00 sec)mysql> #started data writemysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+-------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+-------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 800 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 800 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 0 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+-------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+-------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+-------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 800 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 800 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 0 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+-------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+---------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+---------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 2339336 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 2339336 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 1000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+---------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+---------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+---------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 4677984 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 4677984 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 2000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+---------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+---------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+---------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 8183680 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 8183680 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 3500 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+---------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 10522288 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 10522288 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 4500 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 12860848 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 12860848 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 5500 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 15197872 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 15197872 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 6500 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 16366528 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 16366528 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 7000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 18705264 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 18705264 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 8000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 19873888 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 19873888 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 8500 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 23381064 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 23381064 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 10000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 25719520 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 25719520 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 11000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 28056512 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 28056512 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 12000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 29224976 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 29224976 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 12500 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 32732256 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 32732256 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 14000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+---------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+---------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 2339096 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 2339096 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 1000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+---------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+---------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+---------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 5846496 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 5846496 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 2500 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+---------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+---------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+---------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 9353648 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 9353648 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 4000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+---------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 11690832 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 11690832 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 5000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 14029376 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 14029376 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 6000 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> select * from information_schema.ROCKSDB_CFSTATS cfs where cfs.CF_NAME = 'cf_t1'; +---------+-------------------------------+----------+ | CF_NAME | STAT_TYPE | VALUE | +---------+-------------------------------+----------+ | cf_t1 | NUM_IMMUTABLE_MEM_TABLE | 0 | | cf_t1 | MEM_TABLE_FLUSH_PENDING | 0 | | cf_t1 | COMPACTION_PENDING | 0 | | cf_t1 | CUR_SIZE_ACTIVE_MEM_TABLE | 22212400 | | cf_t1 | CUR_SIZE_ALL_MEM_TABLES | 22212400 | | cf_t1 | NUM_ENTRIES_ACTIVE_MEM_TABLE | 9500 | | cf_t1 | NUM_ENTRIES_IMM_MEM_TABLES | 0 | | cf_t1 | NON_BLOCK_CACHE_SST_MEM_USAGE | 0 | | cf_t1 | NUM_LIVE_VERSIONS | 1 | +---------+-------------------------------+----------+ 9 rows in set (0.00 sec)mysql> exit Bye
I believe the documentation is correct in the sense that MIN_WRITE_BUFFER_NUMBER_TO_MERGE should control the number of immutable memtables required prior to a flush, but this doesn't appear to be the case in my testing.
Thanks!