(mysql.info.gz) Index preloading

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 7.4.6.4 Index Preloading
 ........................
 
 If there are enough blocks in a key cache to hold blocks of an entire
 index, or at least the blocks corresponding to its non-leaf nodes, then
 it makes sense to preload the key cache with index blocks before
 starting to use it. Preloading allows you to put the table index blocks
 into a key cache buffer in the most efficient way: by reading the index
 blocks from disk sequentially.
 
 Without preloading, the blocks still will be placed into the key cache
 as needed by queries. Although the blocks will stay in the cache,
 because there are enough buffers for all of them, they will be fetched
 from disk in a random order, not sequentially.
 
 To preload an index into a cache, use the `LOAD INDEX INTO CACHE'
 statement. For example, the following statement preloads nodes (index
 blocks) of indexes of the tables `t1' and `t2':
 
      mysql> LOAD INDEX INTO CACHE t1, t2 IGNORE LEAVES;
      +---------+--------------+----------+----------+
      | Table   | Op           | Msg_type | Msg_text |
      +---------+--------------+----------+----------+
      | test.t1 | preload_keys | status   | OK       |
      | test.t2 | preload_keys | status   | OK       |
      +---------+--------------+----------+----------+
 
 The `IGNORE LEAVES' modifier causes only blocks for the non-leaf nodes
 of the index to be preloaded. Thus, the statement shown preloads all
 index blocks from `t1', but only blocks for the non-leaf nodes from
 `t2'.
 
 If an index has been assigned to a key cache using a `CACHE INDEX'
 statement, preloading places index blocks into that cache.  Otherwise,
 the index is loaded into the default key cache.
 

Info Catalog

(mysql.info.gz) Midpoint insertion

(mysql.info.gz) MyISAM key cache

(mysql.info.gz) Key cache block size