hashtable - Is there an extensible open address hash table? -

i'm implementing key-value store in memory used real-time service. needs fast , low latency. because number of elements not known in advance, table should grow gradually. prefer open-address hash tables since faster chaining ones. however, open-address hash tables typically require occasional slow rehashs, during service unavailable. not acceptable. on other hand, extensible hash tables typically based on chaining, , slower open address ones.

are there hash tables fast open address ones (like google's dense_hash_map) , not have large rehash overhead?

one simple way use array of k small hash tables, rehash overhead can reduced 1/k. however, doesn't make sense in case, because need reduce total unavailable time rather max unavailable time. if k small hash tables used, although max unavailable time reduced 1/k, rehashs occur k times more often.