Skip to main content

Wal difference in PostgreSQL


Here is the function can calculate the no.of files difference between the two wail files, and will give you an exact results.

CREATE OR REPLACE FUNCTION public.hot_standby_lag(primary_xlog_loc text, slave_xlog_replay_loc text)
 RETURNS integer
 LANGUAGE plpgsql
AS $function$
Digit_Length int;
Query text;
No_of_Bits int;
No_of_Walfiles int;
No_of_Zeros int:=0;
Cnt int:=0;
Re_Formatted_Primary_Log text;
Re_Formatted_Slave_Log text;
_1 int;
_2 int;
_3 int;
select GREATEST(length(trim(substring($1 for 8),'0')||trim(substring($1 from 9 for 8),'0')||ltrim(substring($1 from 17 for 8),'0')),length(ltrim(substring($2 for 8),'0')||trim(substring($2 from 9 for 8),'0')||ltrim(substring($2 from 17 for 8),'0'))) into Digit_Length;

select GREATEST(length(ltrim(substring($1 for 8),'0')),length(ltrim(substring($2 for 8),'0'))) into _1;
select GREATEST(length(trim(substring($1 from 9 for 8),'0')),length(trim(substring($2 from 9 for 8),'0'))) into _2;
select GREATEST(length(ltrim(substring($1 from 17 for 8),'0')),length(ltrim(substring($2 from 17 for 8),'0'))) into _3;

if _3 != 2 then
raise notice 'enterted';
end if;
raise notice '%',Digit_Length;

select ('x'||lpad(ltrim(substring(PRIMARY_XLOG_LOC for 8),'0'),_1,'0')||lpad(trim(substring(PRIMARY_XLOG_LOC from 9 for 8),'0'),_2,'0')||lpad(ltrim(substring(PRIMARY_XLOG_LOC from 17 for 8),'0'),2,'0')) into Re_Formatted_Primary_Log;
Raise notice '%',Re_Formatted_Primary_Log;

select ('x'||lpad(ltrim(substring(SLAVE_XLOG_REPLAY_LOC for 8),'0'),_1,'0')||lpad(trim(substring(SLAVE_XLOG_REPLAY_LOC from 9 for 8),'0'),_2,'0')||lpad(ltrim(substring(SLAVE_XLOG_REPLAY_LOC from 17 for 8),'0'),2,'0')) into Re_Formatted_Slave_Log;
raise notice '%',Re_Formatted_Slave_Log;

select GREATEST(length(regexp_replace(Re_Formatted_Primary_Log::text,'[^0]','','g')),length(regexp_replace(Re_Formatted_Slave_Log::text,'[^0]','','g'))) into Cnt;

Query:='select (select '''||Re_Formatted_Primary_Log||'''::bit('||No_Of_Bits||')::bigint) - (select '''||Re_Formatted_Slave_Log||'''::bit('||No_Of_Bits||')::bigint)';
raise notice '%',Query;
execute query into No_of_Walfiles;
return No_of_Walfiles;

Here, i tweaked the logic behind the hex decimal file names and will give you the exact resutls.

Hope this helps in warm standby/hot standby no.of files delay..



Popular posts from this blog

Pgpool Configuration & Failback

I would like to share the pgpool configuration, and it's failback mechanism in this post.

Hope it will be helpful to you in creating pgpool and it's failback setup.

Pgpool Installation & Configuration

1. Download the pgpool from below link(Latest version is 3.2.1).

2. Untart the pgpool-II-3.2.1.tar.gz and goto pgpool-II-3.2.1 directory.

3. Install the pgpool by executing the below commands:

./configure ­­prefix=/opt/PostgreSQL92/ ­­--with­-pgsql­-includedir=/opt/PostgreSQL92/include/ --with­-pgsql­-libdir=/opt/PostgreSQL92/lib/ make make install 4. You can see the pgpool files in /opt/PostgreSQL92/bin location.
/opt/PostgreSQL92/bin $ ls clusterdb   droplang  pcp_attach_node  pcp_proc_count pcp_systemdb_info  pg_controldata  pgpool pg_test_fsync pltcl_loadmod  reindexdb createdb    dropuser  pcp_detach_node  pcp_proc_info createlang  ecpg      pcp_node_count   pcp_promote_node oid2name  pcp_pool_status  pcp_stop_pgpool  …

pgBucket - A new concurrent job scheduler

Hi All,

I'm so excited to announce about my first contribution tool for postgresql. I have been working with PostgreSQL from 2011 and I'm really impressed with such a nice database.

I started few projects in last 2 years like pgHawk[A beautiful report generator for Openwatch] , pgOwlt [CUI monitoring. It is still under development, incase you are interested to see what it is, attaching the image here for you ],

pgBucket [Which I'm gonna talk about] and learned a lot and lot about PostgreSQL/Linux internals.

Using pgBucket we can schedule jobs easily and we can also maintain them using it's CLI options. We can update/insert/delete jobs at online. And here is its architecture which gives you a basic idea about how it works.

Yeah, I know there are other good job schedulers available for PostgreSQL. I haven't tested them and not comparing them with this, as I implemented it in my way.
Features are: OS/DB jobsCron style sytaxOnline job modificationsRequired cli options

pgBucket 2.0 Beta Is Ready

I am so glad to announce pgBucket 2.0 beta version, which is evolved from the version 1.0. Below are this version feature highlights and hoping that everybody likes these features.

Event jobs (Cascading jobs)Dedicated configuration fileExtended table printAuto job disableCustom job failureDedicated connection poolerImproved the daemon stability/coding standards Please find the below URL for the features review.