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.

                                                   01/31/2014                                     MTBL_WRITER(3)