Re: Postgres PAF setup
On 04/23/2018 08:09 PM, Andrew Edenburn wrote: > I am having issues with my PAF setup. I am new to Postgres and have setup the > cluster as seen below. > > I am getting this error when trying to start my cluster resources. > > > > Master/Slave Set: pgsql-ha [pgsqld] > > pgsqld (ocf::heartbeat:pgsqlms): FAILED dcmilphlum224 > (unmanaged) > > pgsqld (ocf::heartbeat:pgsqlms): FAILED dcmilphlum223 > (unmanaged) > > pgsql-master-ip (ocf::heartbeat:IPaddr2): Started dcmilphlum223 > > > > Failed Actions: > > * pgsqld_stop_0 on dcmilphlum224 'unknown error' (1): call=239, > status=complete, > exitreason='Unexpected state for instance "pgsqld" (returned 1)', > > last-rc-change='Mon Apr 23 13:11:17 2018', queued=0ms, exec=95ms > > * pgsqld_stop_0 on dcmilphlum223 'unknown error' (1): call=248, > status=complete, > exitreason='Unexpected state for instance "pgsqld" (returned 1)', > > last-rc-change='Mon Apr 23 13:11:17 2018', queued=0ms, exec=89ms > > > > cleanup and clear is not fixing any issues and I am not seeing anything in the > logs. Any help would be greatly appreciated. > > Hello Andrew, Could you enable debug logs in Pacemaker? With Centos you have to edit PCMK_debug variable in /etc/sysconfig/pacemaker : PCMK_debug=crmd,pengine,lrmd This should give you more information in logs. Monitor action in PAF should report why the cluster doesn't start : https://github.com/ClusterLabs/PAF/blob/master/script/pgsqlms#L1525 Regards, -- Adrien NAYRAT signature.asc Description: OpenPGP digital signature
Re: Adding AVG to a JOIN
Thank you for the explanation. I have rearranged my query and it works now
(surprisingly fast too) -
On Mon, Apr 23, 2018 at 9:58 PM, David G. Johnston <
david.g.johns...@gmail.com> wrote:
> On Mon, Apr 23, 2018 at 12:47 PM, Alexander Farber <
> alexander.far...@gmail.com> wrote:
>
>> SELECT
>> u.elo,
>> AVG(c.played - c.prev_played) AS
>> avg_time_per_move,
>> (SELECT ROUND(AVG(score), 1) FROM words_moves
>> WHERE uid = u.uid) AS score,
>>
>> And I don't understand why adding a CTE has caused it, because without
>> the CTE the GROUP BY u.elo was not required...
>>
>>
> Adding "AVG(c.played - c.prev_played)" directly to the top-level select
> statement column list is what turned it into a "GROUP BY" query. When you
> embedded the "AVG(score)" in a subquery the GROUP BY was limited to just
> that subquery, and it had no other columns besides the aggregate and so
> didn't require a GROUP BY clause.
>
>
WITH cte AS (
SELECT
m.gid,
m.uid,
m.played,
LAG(m.played) OVER (PARTITION BY m.gid
ORDER BY played) AS prev_played
FROM words_moves m
JOIN words_games g ON (m.gid = g.gid AND m.uid in
(g.player1, g.player2))
WHERE m.played > CURRENT_TIMESTAMP - interval '1
month'
)
SELECT
u.elo,
(SELECT TO_CHAR(AVG(played - prev_played),
'HH24:MI') FROM cte WHERE uid = u.uid) AS avg_time,
(SELECT ROUND(AVG(score), 1) FROM words_moves WHERE
uid = u.uid) AS avg_score,
s.given,
s.photo
FROM words_users u
JOIN words_social s USING (uid)
WHERE u.elo > 1500
-- take the most recent record from words_social
AND NOT EXISTS (SELECT 1
FROM words_social x
WHERE s.uid = x.uid
AND x.stamp > s.stamp)
-- only show players who where active in the last week
AND EXISTS (SELECT 1
FROM words_moves
WHERE played > CURRENT_TIMESTAMP - INTERVAL '1
week'
AND action IN ('play', 'skip', 'swap',
'resign'))
ORDER BY u.elo DESC
LIMIT 10;
Best regards
Alex
Re: Strange error in Windows 10 Pro
Il 24/04/2018 04:09, Dale Seaburg ha scritto: Thanks to Moreno and Igor for the Event Viewer suggestions. Here are a few lines of log file where they differ between a good install and a bad incomplete install. The good install was from my Shop PC with Windows 10 Pro. BTW, I had success with another Dell PC with Win 10 Pro about 4 months ago. This problem appears to be a one-off. Good Install: Called AclCheck(C:\Program Files\PostgreSQL\9.6\data) Called IsVistaOrNewer()... 'winmgmts' object initialized... Version:10. MajorVersion:10 Executing icacls to ensure the SHOP-PC\Dale account can read the path C:\Program Files\PostgreSQL\9.6\data Executing batch file 'rad0510A.bat'... processed file: C:\Program Files\PostgreSQL\9.6\data Successfully processed 1 files; Failed processing 0 files Bad Install: Called AclCheck(D:\PostgreSQL\9.6\data) Called IsVistaOrNewer()... 'winmgmts' object initialized... Version:10. MajorVersion:10 Executing icacls to ensure the WINDOWS-6BEGVO1\don king account can read the path D:\PostgreSQL\9.6\data Executing batch file 'rad6DBC7.bat'... It would be interesting to have the next 2 lines in "Bad install", like in "good install", to know if rad6DBC7.bat excecution terminated with or without errors so if there's an error it would be nice to see it. I assume D: to be a secondary local drive or anyway a local partition not a network or external one... Thanks Moreno.-
Re: Rationale for aversion to the central database?
I have done some big contracts for large financial companies, and for most of them, ANY changes to the DB structure required extensive 3rd party testing and a change control process that sometimes took weeks. But we did get a waiver for the use of DB 'code' like stored procedures and views, which only had to follow the standard development test / acceptance procedure by separate developer, end user and third party test teams. For me, the database is more immutable than the application logic and especially the GUI, so it pays to spend a lot of time up front on DB design. Past experience has also lead me to expect that the DBMS will have a much longer shelf life than the application language / toolsets used against it, or at least, over time the languages / toolsets tend to multiply. For my part, I like to spend a lot of tie in getting an optimal DB design, and also putting a lot of validation logic into the DB. I also like making expensive use of stored procedures, my experience is that for a data-intensive multi-tool application they are faster and more secure... On 23 April 2018 at 19:22, Sven R. Kunze wrote: > So far, I have nothing to add, but just one thing. See below: > > > On 09.04.2018 00:37, g...@luxsci.net wrote: > >> One advantage to using logic and functions in the db is that you can fix >> things immediately without having to make new application builds. That in >> itself is a huge advantage, IMO. >> > > This is actually not the case. You want to have those logic tested as > thoroughly as possible being so close to your precious data. > > So, you write migration code that substitutes the old logic, test the > whole package, if successful, deploy (and thus run the migration). > > Cheers, > Sven > >
Questions on user defined data types
Hi there: I want to ask the if I could define an object like type in postgresql, it may be better to illustrate with actual examples. Background information: 1, I would like to pack group of data into 1 entry of in a table. 2, The table consist some financial product information including names, public data and etc. 3, Each product need to be valued, and the packed entry contains all the assumptions (interest rate, etc.) to perform valuation calculation of the products. Furthermore, for company management purpose, the packed data would have the following properties: 1, Elements of the entry can be easily queried, using SQL; 2, Change of element value is not allowed by simple update, only using pre-complied "methods" functions can update them; 3, Changes using methods functions would be recorded into a specified sub-object called "LOG", which record down update information including update times and etc. I am asking if this could be realized and if yes, how should I do it. Thank you so much ~~ Shore
Re: Questions on user defined data types
On Tue, Apr 24, 2018 at 4:53 AM, a <372660...@qq.com> wrote: > Hi there: > > I want to ask the if I could define an object like type in postgresql, it > may be better to illustrate with actual examples. > > Background information: > > 1, I would like to pack group of data into 1 entry of in a table. > > 2, The table consist some financial product information including > names, public data and etc. > > 3, Each product need to be valued, and the packed entry contains all > the assumptions (interest rate, etc.) to perform valuation calculation of > the products. > > Furthermore, for company management purpose, the packed data would have > the following properties: > > 1, Elements of the entry can be easily queried, using SQL; > > 2, Change of element value is not allowed by simple update, only using > pre-complied "methods" functions can update them; > > 3, Changes using methods functions would be recorded into a specified > sub-object called "LOG", which record down update information including > update times and etc. > > I am asking if this could be realized and if yes, how should I do it. > > What you describe seems doable, at least to some degree. See the documentation for: CREATE TYPE CREATE TABLE CREATE FUNCTION GRANT David J.
Re: rh-postgresql96 vs community postgresql-9.6
On 04/23/2018 08:59 AM, yogeshr wrote: Our client has provided us Red Hat machine for setting up PostgreSQL. We are allowed to install red hat provided packages only. What version of RH? So we have to install red hat provided postgresql (rh-postgresql96) instead of postgresql-9.6. Is it a good approach to go with red hat specific PostgreSQL in production instead of community PostgreSQL? It is the same code so that should not be a problem. The issues would be support and version life: So do you have RH support for longer then 5 years of community support for a version? Will you be able to upgrade to new version in future? Also, we were trying to set up repmgr for this PostgreSQL in the local environment but we didn't find any suitable package for this PostgreSQL. That is something you are going to have to talk over with your client. A RH-provided package only policy is going to prevent them from participating in the diverse third party package community that exists around Postgres. How can we install any high availability solution like repmgr for Red Hat provided PostgreSQL? That is probably some you will have to discuss with RH. any help would be appreciated. -- Sent from: http://www.postgresql-archive.org/PostgreSQL-general-f1843780.html -- Adrian Klaver adrian.kla...@aklaver.com
RE: Strange error in Windows 10 Pro
From: Dale Seaburg [mailto:kg...@verizon.net] Sent: Monday, April 23, 2018 10:10 PM To: pgsql-general@lists.postgresql.org Subject: Re: Strange error in Windows 10 Pro Thanks to Moreno and Igor for the Event Viewer suggestions. Here are a few lines of log file where they differ between a good install and a bad incomplete install. The good install was from my Shop PC with Windows 10 Pro. BTW, I had success with another Dell PC with Win 10 Pro about 4 months ago. This problem appears to be a one-off. Good Install: Called AclCheck(C:\Program Files\PostgreSQL\9.6\data) Called IsVistaOrNewer()... 'winmgmts' object initialized... Version:10. MajorVersion:10 Executing icacls to ensure the SHOP-PC\Dale account can read the path C:\Program Files\PostgreSQL\9.6\data Executing batch file 'rad0510A.bat'... processed file: C:\Program Files\PostgreSQL\9.6\data Successfully processed 1 files; Failed processing 0 files Bad Install: Called AclCheck(D:\PostgreSQL\9.6\data) Called IsVistaOrNewer()... 'winmgmts' object initialized... Version:10. MajorVersion:10 Executing icacls to ensure the WINDOWS-6BEGVO1\don king account can read the path D:\PostgreSQL\9.6\data Executing batch file 'rad6DBC7.bat'... Notice the last four lines of the Good Install vs the last two lines of the Bad Install. There is no indication of processing, or whether it was successful or not in the bad install. As you can see, I even took Igor's suggestion to install in a non-system (Program Files) path, to no success. Again, not sure what to do. Open for suggestions... I'm almost ready to call Dell and complain about a "bad" Win 10 Pro install. Dale Dale, The problem isn’t in “bad” Win10 Pro install. The problem is that Win10 on this machine is configured differently from Win10 machine where your install worked fine. In Windows there is a “default” association between file types/extensions and programs that execute these files by default. Batch files like 'rad6DBC7.bat' shouldn’t have any association, Win OS knows that this type should be executed by OS, like .exe types. But sometimes Windows users change it, and associate .bat files with Notepad (or some other text editor) in order to be able to edit batch scripts. By the way, batch file names are different in “good” and “bad” installations because those are temporary files created by vbs scripts that are running during install. So, in order to fix this you need to dissociate .bat type/extension from Notepad, or whatever text editor it is associated on the “bad” Windows. If you don’t know where to look for this feature in Win OS, ask someone who’s more familiar with windows environment. Pretty sure that’s the solution of your problem. Regards, Igor Neyman
Re: Rationale for aversion to the central database?
On Sun, Apr 8, 2018 at 15:37 g...@luxsci.net wrote: > > > On April 8, 2018 02:40:46 pm PDT, "Guyren Howe" wrote: > > One advantage to using logic and functions in the db is that you can fix > things immediately without having to make new application builds. That in > itself is a huge advantage, IMO. > I doubt most of us would consider this any kind of advantage outside of the momentary temptation to do it when an app is completely broken and needs to be up in a hurry. Application changes, whether in the dB or in application logic, need to be tested, and they need to be revision controlled and released in a manner that can be easily rolled back in an automated manner. The fact that putting logic in the database can effectively allow developers to make unreleased changes to production apps is specifically one of the problems that I am trying to avoid when I keep most logic in the app instead of the dB. It’s a whole lot harder to make arbitrary manual changes to code in the app, whether interpreted or compiled, if it is running inside a container that cannot be updated. Even if you go in with a shell and update an interpreted file, the next time that container is launched the change will be lost, which is usually sufficient motivation to keep devs from doing that kind of thing. I’ll put some things in the db, either for performance or because I want that logic to be built into the data and not be part of the application, but I choose those contexts carefully and I write them in as portable a manner as possible. And for those who say migrations don’t happen, I’ve certainly been through a few, usually as part of an acquisition or the like, but sometimes simply because another dB server better meets our needs after a time. And migrating stored procs can be really difficult. Such code usually has less complete unit and integration tests, which makes validating those changes more difficult, too. But the biggest reason is that databases often have to scale up rather than out, so keeping as much logic in the application code allows my scaling requirements for the dB server to be as minimal as possible. Sure, there are workloads where pushing raw data across the wire will be more work than processing it in the dB, and in those cases, I may do that, but I consider it premature optimization to just assume that is necessary without hard evidence from production examples to suggest otherwise. Finally, there’s the consistency argument. I want to find all of the logic in one place. Either entirely in the source code or entirely in the dB. Having to trace things from the code to the dB and back again can make it a whole lot harder to see, at a glance, what is happening in the code. Having logic in the dB also means it can be difficult or impossible to have two releases talking to the same schema version at the same time - so canary builds and rolling deployments can be difficult. Of course, schema changes can cause this problem, regardless of whether there are stored procs, but the more of your logic that lives in the db, the more likely it is that your releases will conflict over the db. So I’m more likely to be able to do a rolling release if I keep the db as a dumb data store and keep logic in the application code.
Backup Strategy Advise
Hi: I need some advise on how best to backup a PG DB. PG 9.5.2 on RHEL6 The requirement is to be able to restore the DB after catastrophic failure and lose no more than the last 15 minutes worth of data. Also, we would like to be able to do the backups on-line (no down time). There is no need for PITR other than the point in time being the latest possible. Typically, I would think doing a weekly full backup, daily incremental backups and turn on journaling to capture what goes on since the last backup. When DB recovery is needed, restore up to the last daily, then reply the journal to restore up to the last time the journal was flushed to disk (checkpoint=15 minutes). I'm not quite sure if something like this is possible with PG. I've read about the WAL file and wonder if it could be used together with the on-line logical backups (pg_dump) to achieve the 15 minute requirement without needing downtime for physical backups.. Any advise? Thanks in Advance.
Re: Postgres PAF setup
On Mon, 23 Apr 2018 18:09:43 + Andrew Edenburn wrote: > I am having issues with my PAF setup. I am new to Postgres and have setup > the cluster as seen below. I am getting this error when trying to start my > cluster resources. > [...] > > cleanup and clear is not fixing any issues and I am not seeing anything in > the logs. Any help would be greatly appreciated. This lack a lot of information. According to the PAF ressource agent, your instances are in an "unexpected state" on both nodes while PAF was actually trying to stop it. Pacemaker might decide to stop a ressource if the start operation fails. Stopping it when the start failed give some chances to the resource agent to stop the resource gracefully if still possible. I suspect you have some setup mistake on both nodes, maybe the exact same one... You should probably provide your full logs from pacemaker/corosync with timing information so we can check all the messages coming from PAF from the very beginning of the startup attempt. > have-watchdog=false \ you should probably consider to setup watchdog in your cluster. > stonith-enabled=false \ This is really bad. Your cluster will NOT work as expected. PAF **requires** Stonith to be enabled and to properly working. Without it, soon or later, you will experience some unexpected reaction from the cluster (freezing all actions, etc). > no-quorum-policy=ignore \ You should not ignore quorum, even in a two node cluster. See "two_node" parameter in the manual of corosync.conf. > migration-threshold=1 \ > rsc_defaults rsc_defaults-options: \ > migration-threshold=5 \ The later is the supported way to set migration-threshold. Your "migration-threshold=1" should not be a cluster property but a default ressource option. > My pcs Config > Corosync Nodes: > dcmilphlum223 dcmilphlum224 > Pacemaker Nodes: > dcmilphlum223 dcmilphlum224 > > Resources: > Master: pgsql-ha > Meta Attrs: notify=true target-role=Stopped This target-role might have been set by the cluster because it can not fence nodes (which might be easier to deal with in your situation btw). That means the cluster will keep this resource down because of previous errors. > recovery_template=/pgsql/data/pg7000/recovery.conf.pcmk You should probably not put your recovery.conf.pcmk in your PGDATA. Both files are different between each nodes. As you might want to rebuild the standby or old master after some failures, you would have to correct it each time. Keep it outside of the PGDATA to avoid this useless step. > dcmilphlum224: pgsqld-data-status=LATEST I suppose this comes from the "pgsql" resource agent, definitely not from PAF... Regards,
Re: Backup Strategy Advise
On 04/24/2018 07:50 AM, David Gauthier wrote: Hi: I need some advise on how best to backup a PG DB. PG 9.5.2 on RHEL6 The requirement is to be able to restore the DB after catastrophic failure and lose no more than the last 15 minutes worth of data. Also, we would like to be able to do the backups on-line (no down time). There is no need for PITR other than the point in time being the latest possible. Typically, I would think doing a weekly full backup, daily incremental backups and turn on journaling to capture what goes on since the last backup. When DB recovery is needed, restore up to the last daily, then reply the journal to restore up to the last time the journal was flushed to disk (checkpoint=15 minutes). I'm not quite sure if something like this is possible with PG. I've read about the WAL file and wonder if it Pretty sure that won't work. Once you do the restore from the last daily you will change the Postgres files to a state different from the ones captured by the journaling. Replaying the journal will result in a mixture of old and new. could be used together with the on-line logical backups (pg_dump) to achieve the 15 minute requirement without needing downtime for physical backups.. Any advise? Take a look here: https://www.postgresql.org/docs/9.5/static/continuous-archiving.html Thanks in Advance. -- Adrian Klaver adrian.kla...@aklaver.com
Re: Backup Strategy Advise
On Tue, Apr 24, 2018 at 10:50 AM, David Gauthier wrote: > Typically, I would think doing a weekly full backup, daily incremental > backups and turn on journaling to capture what goes on since the last > backup. > This is almost the whole concept of the streaming replication built into postgres, except you are not applying the stream but archiving it. If you have atomic file system snapshots, you can implement this strategy along the lines of marking the DB snapshot for binary backup, snapshot the file system, then copy that snapshot file system off to another system (locally or off-site), meanwhile you accumulate the log files just as you would for streaming replication. Once the copy is done, you can release the file system snapshot and continue to archive the logs similarly to how you would send them to a remote system for being applied. You just don't apply them until you need to do the recovery. Or just set up streaming replication to a hot-standby, because that's the right thing to do. For over a decade I did this with twin servers and slony1 replication. The cost of the duplicate hardware was nothing compared to not having downtime.
Re: Using the public schema
Charlin Barak wrote: > We will be developing three new applications in PostgreSQL, each having its > own > database instance running on different hosts. We will only have one schema per > Postgres instance. The data is read-write only by one application/schema in > the > DB instance and the data is published to other applications via API calls. > > In such a standalone database configuration, are there any security > implications > or any downsides to creating the application in the public schema? No, that's fine. Just REVOKE CREATE ON SCHEMA public FROM PUBLIC. Yours, Laurenz Albe -- Cybertec | https://www.cybertec-postgresql.com
答复: [ClusterLabs] Postgres PAF setup
I have meet the similar issue when the postgres is not stopped normally.
You could run pg_controldata to check if your postgres status is
shutdown/shutdown in recovery.
I change the /usr/lib/ocf/resource.d/heartbeat/pgsqlms to avoid this problem:
elsif ( $pgisready_rc == 2 ) {
# The instance is not listening.
# We check the process status using pg_ctl status and check
# if it was propertly shut down using pg_controldata.
ocf_log( 'debug', 'pgsql_monitor: instance "%s" is not listening',
$OCF_RESOURCE_INSTANCE );
# return _confirm_stopped(); # remove this line
return $OCF_NOT_RUNNING;
}
-邮件原件-
发件人: Users [mailto:users-boun...@clusterlabs.org] 代表 Adrien Nayrat
发送时间: 2018年4月24日 16:16
收件人: Andrew Edenburn ; pgsql-gene...@postgresql.org;
us...@clusterlabs.org
主题: Re: [ClusterLabs] Postgres PAF setup
On 04/23/2018 08:09 PM, Andrew Edenburn wrote:
> I am having issues with my PAF setup. I am new to Postgres and have
> setup the cluster as seen below.
>
> I am getting this error when trying to start my cluster resources.
>
>
>
> Master/Slave Set: pgsql-ha [pgsqld]
>
> pgsqld (ocf::heartbeat:pgsqlms): FAILED dcmilphlum224
> (unmanaged)
>
> pgsqld (ocf::heartbeat:pgsqlms): FAILED dcmilphlum223
> (unmanaged)
>
> pgsql-master-ip (ocf::heartbeat:IPaddr2): Started
> dcmilphlum223
>
>
>
> Failed Actions:
>
> * pgsqld_stop_0 on dcmilphlum224 'unknown error' (1): call=239,
> status=complete, exitreason='Unexpected state for instance "pgsqld"
> (returned 1)',
>
> last-rc-change='Mon Apr 23 13:11:17 2018', queued=0ms, exec=95ms
>
> * pgsqld_stop_0 on dcmilphlum223 'unknown error' (1): call=248,
> status=complete, exitreason='Unexpected state for instance "pgsqld"
> (returned 1)',
>
> last-rc-change='Mon Apr 23 13:11:17 2018', queued=0ms, exec=89ms
>
>
>
> cleanup and clear is not fixing any issues and I am not seeing
> anything in the logs. Any help would be greatly appreciated.
>
>
Hello Andrew,
Could you enable debug logs in Pacemaker?
With Centos you have to edit PCMK_debug variable in /etc/sysconfig/pacemaker :
PCMK_debug=crmd,pengine,lrmd
This should give you more information in logs. Monitor action in PAF should
report why the cluster doesn't start :
https://github.com/ClusterLabs/PAF/blob/master/script/pgsqlms#L1525
Regards,
--
Adrien NAYRAT
Re: rh-postgresql96 vs community postgresql-9.6
On 04/24/2018 10:06 PM, Adrian Klaver wrote: > On 04/23/2018 08:59 AM, yogeshr wrote: (...) >> Also, we were trying to set up repmgr for this PostgreSQL in the local >> environment but we didn't find any suitable package for this PostgreSQL. > > That is something you are going to have to talk over with your client. > A RH-provided package only policy is going to prevent them from participating > in the diverse third party package community that exists around Postgres. Indeed; the RedHat packages seem to use a completely different file system layout to the community packages, so many if not most community packages are unlikely to work even if force-installed. >> How can we install any high availability solution like repmgr for Red Hat >> provided PostgreSQL? > > That is probably some you will have to discuss with RH. Other possibilities would be: a) compile the package from source (not an efficient method of deployment, not desirable to do on production machines and often not possible), b) create your own RPMs compatible with the RedHat ones (community spec files are available here: https://git.postgresql.org/gitweb/?p=pgrpms.git ), or c) persuade your client to switch to a support provider who provides support based around community packages (there are a number, including the one mentioned in my email signature). Regards Ian Barwick -- Ian Barwick http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
Strange Index sizes
Hi all, I have a user table with ~8M records, with different type of fields b-tree indexed. by investigating index sizes, i found two strange things: 1- all index sizes are almost the same, regardless of field type (boolean, string, bigint) 2 - all of them are much bigger that my expectation, e.g. for a boolean field, even after reindexing, the size is 217MB, so each record takes ~27 bytes. could some one shed some light on this please? or refer any user oriented documentation about index size estimations
Questions on input function of TOAST enabled user defined types
The normal input function for variables with properties of {internallength!=
variable, storage=plain/main}, the return type will be Datum.
The definition of Datum is "unsigned __int64" which may only consist the
address of pointed data.
For data with variable length, the length of the data is also needed, so Datum
type would be not enough since it only provide a pointer to the data.
So what should I do if I would have a TOAST enabled user defined data types,
should I use other type such as struct varlena as return type??
Thanks so much!!
