Option String and Option Map

Users pass options to RocksDB through Options class. Other than setting options in the Options class, there are two other ways to set it:

1. get an option class from an option file.
2. get it from an option string by calling
3. get it from a string map

To get an option from a string, call GetColumnFamilyOptionsFromString() or GetDBOptionsFromString() with a string containing the information. There is also a special GetBlockBasedTableOptionsFromString() and GetPlainTableOptionsFromString() to get table specific option.

An example of an option string will like this:

write_buffer_size=10;max_write_buffer_number=16;plain_table_factory={user_key_len=66;bloom_bits_per_key=20;};arena_block_size=1024

Each option will be given as <option_name>:<option_value> separated by ;. The <option_name> always map the option name in the DBOptions and ColumnFamilyOptions class. You can find the list of options and their descriptions in those two classes in the source file Options.h of the source code of your release. Note that although most of the options are supported in the option string, there are exceptions. You can find the list of supported options in variable db_options_type_info, cf_options_type_info and block_based_table_type_info in the source file util/options_helper.h of the source code of your release.