![\"\"](\"http:\/\/pgdataeraold.local\/wp-content\/uploads\/2023\/09\/image.png\")
<\/figure>\n\n\n\n\n\n\n\n
Postgresql Instance: It consists of background processes, helper processes, and a While starting, the following logs can be seen.<\/p>\n\n\n\n When we execute The daemon process listens for connection requests from clients and creates a server\/ Note: Having an extension line between two departments in your office indicates that When users connect to the database, they usually want to read ( The architecture of Postgresql consists of 3 main components: Postgresql Instance: It consists of background processes, helper processes, and ashared buffer area.The postmaster process manages the instance. An instance can only manage adatabase cluster and its databases (Cluster concept is explained in detail in Storagetopic).More than one instance can run on the same server at … PostgreSQL Architecture Overview<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[277],"tags":[],"class_list":["post-81","post","type-post","status-publish","format-standard","hentry","category-postgresql-database-architecture"],"_links":{"self":[{"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/posts\/81","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/comments?post=81"}],"version-history":[{"count":0,"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/posts\/81\/revisions"}],"wp:attachment":[{"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/media?parent=81"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/categories?post=81"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/pgdataera.com\/en\/wp-json\/wp\/v2\/tags?post=81"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
shared buffer area.<\/mark>
The postmaster process manages the instance. An instance can only manage a
database cluster and its databases (Cluster concept is explained in detail in Storage
topic).
More than one instance can run on the same server at the same time, provided that
they are on different TCP ports.
The tasks of instance are Read\/write (I\/O), provision of ACID conditions, a connection
of client processes, access control, recovery\/restore, replication, etc.
When the database is started with systemctl<\/code><\/code> or pg_ctlcluster (pg_cluster)<\/code>, it assigns the memory from the operating system according to the
memory settings in the configuration file, starts the processes, and makes it available
for the clients to access.<\/p>\n\n\n\nWhen the instance is stopped;\nroot@srv2:~# ps f -upostgres\nroot@srv2:~# top -u postgres\nPID TTY STAT TIME COMMAND\ntop - 19:19:21 up 6:45, 2 users, load average: 0.00, 0.00, 0.00\nTasks: 75 total, 1 running, 74 sleeping, 0 stopped, 0 zombie\n%Cpu(s): 0.0 us, 0.7 sy, 0.0 ni, 99.3 id, 0.0 wa, 0.0 hi,0.0 si, 0.0 st\nMiB Mem : 1995.4 total, 1601.4 free, 107.2 used, 286.8 buff\/cache\nMiB Swap: 0.0 total, 0.0 free, 0.0 used. 1718.0 avail Mem\nPID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND<\/pre>\n\n\n\n
\n\n\n\nps f -upostgres<\/code> ve top -u postgres<\/code>
When we check with the above commands, no postgresql processes or postgres users
are listed.<\/p>\n\n\n\nWhen the Instance is started:\n# root kullan\u0131c\u0131s\u0131 ile ya da sudo yetkisi olan bir kullan\u0131c\u0131 \nile ba\u015f\u0131na \u201c sudo \u201d ekleyerek;\n\nsystemctl start postgresql\n\n# logu izleyelim, log dosyas\u0131n\u0131n ismi sizde farkl\u0131 olabilir \n\u201cls-ltr \u201d ile s\u0131ralay\u0131p en g\u00fcncel olan\u0131 kullanabilirsiniz.\n\ntail -f \/var\/log\/postgresql\/postgresql-13-main.log<\/pre>\n\n\n\n
\n\n\n\n#Another instance\n\/pg\/13.4\/bin\/pg_ctl -D \/pgdata\/13.4 -l pg_$DATE.log start\npostgres@srv2:~$ ps f -upostgres\n\/pg\/13.4\/bin\/postgres -D \/pgdata\/13.4\n_ postgres: checkpointer\n_ postgres: background writer\n_ postgres: walwriter\n_ postgres: autovacuum launcher\n_ postgres: stats collector\n_ postgres: logical replication launcher<\/pre>\n\n\n\n
\n\n\n\nps f -upostgres<\/code> and top -u postgres<\/code> again, it lists
the processes that are opened and the instance assigns memory from the operating
system. This shows that the resources have been used.<\/p>\n\n\n\nPostgresql Connections<\/h2>\n\n\n
![\"\"](\"http:\/\/pgdataeraold.local\/wp-content\/uploads\/2023\/11\/image-18.png\")
<\/figure><\/div>\n\n\n
\n\n\n\n
backend process for each incoming connection request. When the daemon process is
not running, a connection over the network cannot be made.
When the client sends a connection request, the daemon process fulfills this request
and creates a backend process. After the backend process has been authenticated,
query, data entry\/update etc. coming from the client (client) is processed. The backend
process acts as the user\u2019s agent.
These processes are repeated for each incoming connection request and server\/
backend processes are created as many as the number of connections, up to themax_connection<\/code> limit.<\/p>\n\n\n\n
the connection exists. Whenever one calls the other and the other party opens and
starts the communication, the session is started.<\/mark><\/p>\n\n\n\n![\"\"](\"http:\/\/pgdataeraold.local\/wp-content\/uploads\/2023\/11\/image-20.png\")
<\/figure>\n\n\n\n
\n\n\n\nselect<\/code>) or write
(DML=insert\/update\/delete<\/code>) data. Software developers generally need
operations such as adding columns\/indexes to the table.
Multiple connections can be made at the same time with the same user.<\/p>\n","protected":false},"excerpt":{"rendered":"