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Re: Please review MDEV-17832 Protocol: extensions for Pluggable types and JSON, GEOMETRY


Hi Bar,

2 things I'd like to change:

+typedef struct st_mariadb_metadata_string
+  const char *str;
+  size_t length;

We already have MYSQL_LEX_STRING for dynamic columns and MARIADB_STRING for
replication API.
I think we should just move MARIADB_STRING from mariadb_rpl.h to mysql.h
and use it instead.

+  mariadb_field_metadata_attr(const MYSQL_FIELD *field,
+                              enum mariadb_field_metadata_attr_t type);

I think we should have a more general function, so that we don't need to
add a new function when
we need to extend MYSQL_FIELD (but it can be used also for retrieving
values from other members of MYSQL_FIELD):

enum mariadb_field_info_type {
  /* Later I can add

my_bool STDCALL mariadb_get_field_info(const MYSQL_FIELD *field,
                                       enum mariadb_field_info_type,
                                       void *arg, ..)

We have a similiar function in mariadb_lib.c: mariadb_get_infov():
Also the function needs to be added to the MARIADB_SYMBOLS in

Otherwise it looks ok!


On Wed, Feb 26, 2020 at 3:40 PM Alexander Barkov <bar@xxxxxxxxxxx> wrote:

> Hi, Sergei, Georg,
> Please review a fixed version of the patch for MDEV-17832.
> There are two files attached:
> - mdev-17821.v18.diff     (server changes)
> - mdev-17821-cli.v06.diff (libmariadb changes)
> Comparing to the previous version, this version:
> 1. Adds a new structure MA_FIELD_EXTENSION
> 2. Moves extended data type information from MYSQL_FIELD
>     to MYSQL_FIELD::extension in the client-server implementation.
>     Note, in case of embedded server, the extended metadata
>     is stored directly to MYSQL_FIELD.
> 3. Adds a new API function mariadb_field_metadata_attr(),
>     to extract metadata from MYSQL_FIELD.
> 4. Changes the way how the metadata is packed on the wire
>     from "easily human readable" to "easily parse-able", which:
>     - makes the things faster
>     - allows to transfer arbitrary binary data in the future, if needed.
> Every metadata chunk is now encoded as:
> a. chunk type (1 byte)
> b. chunk data length (1 byte)
> c. chunk data (according to #b)
> For now, two chunk types are implemented:
> - data type name (used for GEOMETRY sub-types, and for INET6)
> - format name (for JSON)
> Thanks!

Georg Richter, Senior Software Engineer
MariaDB Corporation Ab

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