mtbl_info(1) [debian man page]

MTBL_INFO(1)															      MTBL_INFO(1)

NAME

       mtbl_info - display information about an MTBL file

SYNOPSIS

       mtbl_info FILE [FILE]...

DESCRIPTION

       mtbl_info(1) displays the following information about the MTBL files specified on the command line.

       file name -- the name of the MTBL file.

       file size -- the total size of the MTBL file, in bytes.

       index bytes -- the total number of bytes and proportion of the total file size consumed by the index.

       data block bytes -- the total number of bytes and proportion of the total file size consumed by data blocks.

       data block size -- the maximum size of an uncompressed data block.

       data block count -- the total number of data blocks.

       entry count -- the total number of key-value entries.

       key bytes -- the total number of bytes that all keys in the file would occupy if stored end-to-end in a byte array with no delimiters.

       value bytes -- the total number of bytes that all values in the file would occupy if stored end-to-end in a byte array with no delimiters.

       compression algorithm -- the algorithm used to compress data blocks. Possible values are "none", "snappy" and "zlib".

       compactness -- a rough metric comparing the total number of bytes in the key-value entries with the total size of the MTBL file. It is
       calculated as (file size) / (key bytes + value bytes), and thus takes into account the gains of data block compression and prefix key
       compression against the overhead of the index, trailer, and data block offset arrays.

								    05/29/2012							      MTBL_INFO(1)

MTBL_WRITER(3)															    MTBL_WRITER(3)

NAME

       mtbl_writer - create an MTBL file

SYNOPSIS

       #include <mtbl.h>

       Writer objects:

       struct mtbl_writer *
       mtbl_writer_init(const char *fname, const struct mtbl_writer_options *wopt);

       struct mtbl_writer *
       mtbl_writer_init_fd(int fd, const struct mtbl_writer_options *wopt);

       void
       mtbl_writer_destroy(struct mtbl_writer **w);

       mtbl_res
       mtbl_writer_add(struct mtbl_writer *w,
	       const uint8_t *key, size_t len_key,
	       const uint8_t *val, size_t len_val);

       Writer options:

       struct mtbl_writer_options *
       mtbl_writer_options_init(void);

       void
       mtbl_writer_options_destroy(struct mtbl_writer_options **wopt);

       void
       mtbl_writer_options_set_compression(
	       struct mtbl_writer_options *wopt,
	       mtbl_compression_type compression_type);

       void
       mtbl_writer_options_set_block_size(
	       struct mtbl_writer_options *wopt,
	       size_t block_size);

       void
       mtbl_writer_options_set_block_restart_interval(
	       struct mtbl_writer_options *wopt,
	       size_t block_restart_interval);

DESCRIPTION

       MTBL files are written to disk by creating an mtbl_writer object, calling mtbl_writer_add() for each key-value entry, and then calling
       mtbl_writer_destroy().

       mtbl_writer_add() copies key-value pairs from the caller into the mtbl_writer object. Keys are specified as a pointer to a buffer, key, and
       the length of that buffer, len_key. Values are specified as a pointer to a buffer, val, and the length of that buffer, len_val.

       Keys must be in sorted, lexicographical byte order. The same key may not be added to an mtbl_writer more than once. If the input entries
       are not sorted or may contain duplicate keys, then the mtbl_sorter(3) interface should be used instead.

       mtbl_writer objects may be created by calling mtbl_writer_init() with an fname argument specifying a filename to be created. The filename
       must not already exist on the filesystem. Or, mtbl_writer_init_fd() may be called with an fd argument specifying an open, writable file
       descriptor. No data may have been written to the file descriptor.

       If the wopt parameter to mtbl_writer_init() or mtbl_writer_init_fd() is non-NULL, the parameters specified in the mtbl_writer_options
       object will be configured into the mtbl_writer object.

   Writer options
       compression
	   Specifies the compression algorithm to use on data blocks. Possible values are MTBL_COMPRESSION_NONE, MTBL_COMPRESSION_SNAPPY, or
	   MTBL_COMPRESSION_ZLIB (the default).

       block_size
	   The maximum size of uncompressed data blocks, specified in bytes. The default is 8 kilobytes.

       block_restart_interval
	   How frequently to restart intra-block key prefix compression. The default is every 16 keys.

RETURN VALUE

       mtbl_writer_init() and mtbl_writer_init_fd() return NULL on failure, and non-NULL on success.

       mtbl_writer_add() returns mtbl_res_success if the key-value entry was successfully copied into the mtbl_writer object, and mtbl_res_failure
       if not, for instance if there has been a key-ordering violation.

								    05/29/2012							    MTBL_WRITER(3)