Hash table reallocation (rehashing)

Question

Hello!
I use embedded Berkeley DB to store millions of small items (key ~ 16 byte, value ~ 16 byte). The exact number of items couldn't be known at the time of hash table allocation, so i push to set_h_nelem amount about 100 millions. After some period of time hash table becomes full and i need to rebuild (reallocate) it to avoid lacks in performance.
Does anyone know how to initiate manual hash table reallocation (to expand it) (C/C++ API is prefered)?

Answer 1

Hi,
Just go thro' this.
1. Types of internal tables
1.1 STANDARD table
Key access to a standard table uses a linear search. This means that the time required for a search is in linear relation to the number of table entries.
You should use index operations to access standard tables.
1.2 SORTED table
Defines the table as one that is always saved correctly sorted.
Key access to a sorted table uses a binary key. If the key is not unique, the system takes the entry with the lowest index. The runtime required for key access is logarithmically related to the number of table entries.
1.3 HASHED table
Defines the table as one that is managed with an internal hash procedure
You can only access a hashed table using the generic key operations or other generic operations ( SORT, LOOP, and so on). Explicit or implicit index operations (such as LOOP ... FROM oe INSERT itab within a LOOP) are not allowed.
1.4 INDEX table
A table that can be accessed using an index.
Index table is only used to specify the type of generic parameters in a FORM or FUNCTION. That means that you can't create a table of type INDEX.
Standard tables and sorted tables are index tables.
1.5 ANY table
Any table is only used to specify the type of generic parameters in a FORM or FUNCTION. That means that you can't create a table of type ANY.
Standard, sorted and hashed  tables belongs to ANY tables.