Hi Mark,
Thanks for your speedy reply.
I appreciate the difficulties caused by the changes to My SQL 8. I
personally believe in the importance of preserving backwards
compatibility, and this is a classic example of the externalised costs
that arise from breaking that.
I'm glad you sometimes get an itch to make progress on this. I read that
MySQL is the second-most popular database, so it would be great if
GeoTools/GeoServer could get working with it again, even though the
questionable design decisions were taken elsewhere.
Please keep scratching when you can.
Best wishes,
Martin
------ Original Message ------
From: "mark" <mc.pr...@gmail.com>
To: geotools-devel@lists.sourceforge.net
Sent: 28-Oct-2020 10:02:15
Subject: Re: [Geotools-devel] MySQL 8.0 spatial functions name change
bug
As the doc [https://docs.geoserver.org/latest/en/user/data/database/mysql.html]
says MySQL is an unmaintained and unsupported extension in GeoServer, basically
that means it gets worked on when someone receives an incentive or gets an itch.
To scratch my itch I've started working on MySQL 8 support but ran out of time.
MySQL/Oracle has added a (imo) broken definition of geography complicating
things, only partly supporting version 8 doesn't seem like a great idea to me.
Simple things like getting the envelope are unsupported for geographic CRS in
the database in version 8 while they worked in earlier versions - mainly
because everything was treated like a cartesian CRS.
I've just pushed my work-in-progress online to:
https://github.com/geotools/geotools/pull/3191
see also:
- https://osgeo-org.atlassian.net/browse/GEOT-6690
- https://osgeo-org.atlassian.net/browse/GEOT-6692
-
https://sourceforge.net/p/geotools/mailman/geotools-devel/thread/CA%2BnxMTsqPczfDQfOb0b79dqaWpTERwCLXeVCR9%3DJ_a2qN9-%3Drw%40mail.gmail.com/#msg37098942
Mark
On 10/27/20 8:29 PM, Martin Baxter via GeoTools-Devel wrote:
Dear GeoTools developers,
I'm new to your project but have been using GeoServer happily for several
years.
I tried a recent upgrade to MySQL 8.0 and discovered that the MySQL team have
made some non-backwards compatible changes which have broken GeoTools. That's a
shame since MySQL 8 has been around since April 2018 and it would be great to
have GeoTools compatible with it.
I know from an earlier thread that there are two distinct problems. The harder
problem is that MySQL have changed how they handle geography and SRIDs, and
they have changed the order of the co-ordinates in a SRID-dependent way.
But there is also an easier problem, which is that they have switched off the functions "AsWKB" and
"Envelope" and replaced them with "ST_AsBinary" and "ST_Envelope". I know that GeoTools
developers tried to be ready for this change, but missed a couple of instances.
I'm not a Java developer myself, but it looks like the problem is concentrated
in one file:
geotools-24.0\modules\plugin\jdbc\jdbc-mysql\src\main\java\org\geotools\data\mysql\MySQLDialect.java
Around line 228 where the existing code
sql.append("asWKB(");
needs to be replaced with code like
if (usePreciseSpatialOps) {
sql.append("ST_AsBinary(");
} else {
sql.append("asWKB(");
}
And lines 234-5 could change from
sql.append("asWKB(");
sql.append("envelope(");
to something like
if (usePreciseSpatialOps) {
sql.append("ST_AsBinary(");
sql.append("ST_Envelope(");
} else {
sql.append("asWKB(");
sql.append("envelope(");
}
Is it possible for someone to make the easy change and release a new version of
GeoTools? That would let GeoServer partially operate with MySQL 8.0, and cure
the current show-stopping bug. I understand that the SRID changes are harder,
but not everyone is dependent on that fix. It would be great to get the simple
bug out of the way.
Many thanks for reading this far,
Best wishes,
Martin
Martin Baxter
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