pg_gather mainly targets the use for PostgreSQL versions 10 onwards. But still it is possible to collect and analyze data from older versions. This page covers the special attentions required if PostgreSQL version is older than 10
The amount of information available from views like pg_stat_activity is significantly changed over versions. Ensuring backward compatibility with PostgreSQL version 9.6 and older, without sacrificing features is a tough task. Another challenge is that psql utility of older versions don't have sufficient feautre for data collection without causing any additional overhead and complexity.
However, The project is striving hard to ensure the minimum support for older versions.
Please expect error messages while collecting the data. This is because old versions don't have many features, performance views, columns etc which the script is looking for. However, pg_gather is envisioned to handle failure scenarios, collect the possible data, and perform analysis on what is available.
So you may just ignore the error messages and proceed.
Due to missing features in old psql versions, there could be multiple lines as follows in the output file (The out.txt where the data is collected)
COPY pg_get_activity (datid, pid ,usesysid ,application_name ,state ,query ,wait_event_type ,wait_event ,xact_start ,query_start ,backend_start ,state_change ,client_addr, client_hostname, client_port, backend_xid ,backend_xmin, backend_type,ssl ,sslversion ,sslcipher ,sslbits ,ssl_client_dn ,ssl_client_serial,ssl_issuer_dn ,gss_auth ,gss_princ ,gss_enc,leader_pid,query_id) FROM stdin;
COPY pg_get_activity (datid, pid ,usesysid ,application_name ,state ,query ,wait_event_type ,wait_event ,xact_start ,query_start ,backend_start ,state_change ,client_addr, client_hostname, client_port, backend_xid ,backend_xmin, backend_type,ssl ,sslversion ,sslcipher ,sslbits ,sslcompression ,ssl_client_dn ,ssl_client_serial,ssl_issuer_dn ,gss_auth ,gss_princ ,gss_enc,leader_pid) FROM stdin;
COPY pg_get_activity (datid, pid ,usesysid ,application_name ,state ,query ,wait_event_type ,wait_event ,xact_start ,query_start ,backend_start ,state_change ,client_addr, client_hostname, client_port, backend_xid ,backend_xmin, backend_type,ssl ,sslversion ,sslcipher ,sslbits ,sslcompression ,ssl_client_dn ,ssl_client_serial,ssl_issuer_dn ,gss_auth ,gss_princ ,gss_enc) FROM stdin;
COPY pg_get_activity (datid, pid ,usesysid ,application_name ,state ,query ,wait_event_type ,wait_event ,xact_start ,query_start ,backend_start ,state_change ,client_addr, client_hostname, client_port, backend_xid ,backend_xmin, backend_type,ssl ,sslversion ,sslcipher ,sslbits ,sslcompression ,ssl_client_dn ) FROM stdin;
These duplicate lines, which are not relevant for the old versions, can cause errors while importing the data. All these duplicate lines (multiple lines) need to be replaced with a single line according to the data available for the particular PG version. Following are the samples for few PG versions
COPY pg_get_activity (datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,ssl_client_dn ) FROM stdin;
COPY pg_get_activity (datid,pid,usesysid,application_name,state,query,wait_event_type,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,ssl_client_dn ) FROM stdin;
COPY pg_get_activity (datid,pid,usesysid,application_name,state,query,wait_event_type,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port ) FROM stdin;
if you are using a specific version of PG, you may please use a query as follows to understand the columns involved
select * from pg_stat_get_activity(NULL) limit 0;
Additional contributions are welcome, and please raise issue if something is not working.