# How to Configure RocksDB Block-Cache (1/4)

+ The Get operation tries to read data from the memtable. If it cannot find data, it reads data from the SST file. 
+ The block-cache caches the decompressed data from the SST file to speed up querying.
+ Because the compression ratio for the testing data is about 4, reserve a proper memory space for the page-cache when configuring the block cache.
sst
sst
sst
sst
sst
sst
+ Disk
memtable
+ Memory
block-cache
System
page-cache
+ Decompress data and fill it in the block-cache
+ Fill it in the system page-cache before decompressing data
+ get
+ Tip:
+ The larger the memory space reserved for the page-cache is, the more read hot data that can be cached in the memory there will be (because the page-cache caches the compressed data). But when reading data, more decompression operations might be triggered.
------------------------------------------------------------