* SORT: Don't copy the list into a vector when BY argument is constant.
* Write the hash table size of every db in the dump, so that Redis can resize the hash table just one time when loading a big DB.
* Read-only mode for slaves.
+* Redis big lists as linked lists of small ziplists?
+ Possibly a simple heuristic that join near nodes when some node gets smaller than the low_level, and split it into two if gets bigger than high_level.
REPORTING
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