NAME

       osmium-index-types - Index types used to store node locations

DESCRIPTION

       The  osmium  add-locations-to-ways and osmium export commands have to keep an index of the
       node locations in memory or in a temporary file on disk while doing their work.  There are
       several different ways this can be done which have different advantages and disadvantages.

       Use  the --show-index-types/-I option on these commands to show all available index types.
       It depends on your operating system which index types are available.

       Use the --index-type/-i option on these commands to set the index type to be used.

       The default index type is flex_mem which will keep all data in memory and works for  small
       extracts  as  well  as  the  whole planet file.  It is the right choice for almost all use
       cases if you have enough memory to keep the whole index in memory.

       For the osmium export command, the special type none is used when reading from files  with
       the  node locations on the ways.  (See osmium-add-node-locations-to-ways(1) for how to get
       a file like this.)

       You can use one of the file-based indexes for the node location store to  minimize  memory
       use,  but performance will suffer.  In this case use sparse_file_array if you have a small
       or medium sized extract and dense_file_array if you are working with a full  planet  or  a
       really large extract.

       When using the file-based index types (*_file_array), add the filename you want to use for
       the index after a comma to the index types like so:

       ... -i dense_file_array,index.dat ...

MEMORY USE

       It depends on the index type used how much memory is needed:

       • For sparse_*_array types 16 bytes per node in the input file are used.

       • For dense_*_array types 8 bytes times the largest node ID in the input file are used.

       The *_mem_* types use potentially up to twice this amount.

       The *mem* and *mmap* types store the data in memory, the *file* types in a file on disk.

       The flex_mem type automatically switches between something  similar  to  sparse_mmap_array
       for smaller extracts and dense_mmap_array for larger extracts or the whole planet file.

       If  you  specify the --verbose/-v option, Osmium will display how much memory was used for
       the index.

SEE ALSO

       • osmium(1), osmium-add-locations-to-ways(1), osmium-export(1)

       • Osmium website (https://osmcode.org/osmium-tool/)

       • Index types (https://osmcode.org/osmium-concepts/#indexes)

COPYRIGHT

       Copyright (C) 2013-2019 Jochen Topf <jochen@topf.org>.

       License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.   This  is
       free  software:  you are free to change and redistribute it.  There is NO WARRANTY, to the
       extent permitted by law.

CONTACT

       If   you   have   any   questions   or   want   to   report   a   bug,   please   go    to
       https://osmcode.org/contact.html

AUTHORS

       Jochen Topf <jochen@topf.org>.

                                              1.11.1                        OSMIUM-INDEX-TYPES(5)