mirrors
/
postgres
mirror of https://github.com/postgres/postgres
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Update FAQ_DEV.

This commit is contained in:
Bruce Momjian 2000-11-04 17:09:24 +00:00
parent b61f681f23
commit 6952b3196b
2 changed files with 26 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
doc/FAQ_DEV
View File

@ -26,6 +26,7 @@
10) What is elog()?
11) What is configure all about?
12) How do I add a new port?
13) What is CommandCounterIncrement()?
_________________________________________________________________
1) What tools are available for developers?
@ -414,3 +415,15 @@ c-mode)
src/include/storage/s_lock.h for your CPU. There is also a
src/makefiles directory for port-specific Makefile handling. There is
a backend/port directory if you need special files for your OS.
13) What is CommandCounterIncrement()?
Normally, transactions can not see the rows they modify. This allows
UPDATE foo SET x = x + 1 to work correctly.
However, there are cases where a transactions needs to see rows
affected in previous parts of the transaction. This is accomplished
using a Command Counter. Incrementing the counter allows transactions
to be broken into pieces so each piece can see rows modified by
previous pieces. CommandCounterIncrement() increments the Command
Counter, creating a new piece of the transaction.

13
doc/src/FAQ/FAQ_DEV.html
View File

@ -38,6 +38,7 @@ tables from the backend code?<BR>
<a href="#10">10</a>) What is elog()?<BR>
<a href="#11">11</a>) What is configure all about?<BR>
<a href="#12">12</a>) How do I add a new port?<BR>
<a href="#13">13</a>) What is CommandCounterIncrement()?<BR>
<BR>
<HR>
@ -481,6 +482,18 @@ appropriate values. Hopefully, there is already locking code in
There is a <I>backend/port</I> directory if you need special files for
your OS.<P>
<H3><a name="13">13</a>) What is CommandCounterIncrement()?</H3><P>
Normally, transactions can not see the rows they modify. This allows <CODE>
UPDATE foo SET x = x + 1</CODE> to work correctly.
<P>
However, there are cases where a transactions needs to see rows affected
in previous parts of the transaction. This is accomplished using a
Command Counter. Incrementing the counter allows transactions to be
broken into pieces so each piece can see rows modified by previous
pieces. <I>CommandCounterIncrement()</I> increments the Command
Counter, creating a new piece of the transaction. <P>
</BODY>
</HTML>