This topic describes monitoring metrics related to the cache size within an OceanBase Database tenant. You can specify a statistical period to query statistics about the cache size in a single zone or on a single OBServer of an OceanBase Database tenant.
block_cache
Definition
The size of a block cache in the specified statistical period.
A block cache is similar to a buffer cache in Oracle Database and is used to store data blocks. To be specific, a block cache stores decompressed microblocks whose sizes swell after decompression.
Description
| Metric | Metric field name | Unit |
|---|---|---|
| block_cache | block_cache_size | Megabytes |
Calculation expression
sum(ob_cache_size_bytes{cache_name="user_block_cache",@LABELS}) by (@GBLABELS) / 1048576
row_cache
Definition
The size of a row cache in the specified statistical period.
A row cache stores data rows. After you call the Get or MultiGet method, the data rows returned may be stored in a row cache. This greatly facilitates the query of frequently queried rows.
Description
| Metric | Metric field name | Unit |
|---|---|---|
| row_cache | row_cache_size | Megabytes |
Calculation expression
sum(ob_sysstat{stat_id="120008",@LABELS}) by (@GBLABELS)
plan_cache
Definition
The size of a plan cache in the specified statistical period.
Description
| Metric | Metric field name | Unit |
|---|---|---|
| plan_cache | plan_cache_size | Megabytes |
Calculation expression
sum(ob_plan_cache_memory_bytes{@LABELS}) by (@GBLABELS) / 1048576