Skip to content

P
Postgres FD Implementation
Commit 63f1ccd8 authored by Bruce Momjian's avatar Bruce Momjian
Browse files
Options

Remove src/tool/backend, now that the content is on the web site and wiki.

parent 2042185b
Expand all Hide whitespace changes
Inline Side-by-side
Showing with 0 additions and 651 deletions
src/tools/backend/README deleted 100644 → 0
View file @ 2042185b
src/tools/backend/README
Just point your browser at the index.html file, and click on the
flowchart to see the description and source code.
src/tools/backend/backend_dirs.html deleted 100644 → 0
View file @ 2042185b
This diff is collapsed.
src/tools/backend/flow.fig deleted 100644 → 0
View file @ 2042185b
#FIG 3.2 Produced by xfig version 3.2.5
Portrait
Center
Inches
Letter
88.00
Single
-2
1200 2
0 32 #919191
0 33 #c5ddc1
2 4 0 1 -1 26 1 0 20 0.000 0 0 7 0 0 5
3600 900 1200 900 1200 300 3600 300 3600 900
2 4 0 1 -1 4 1 0 20 0.000 0 0 7 0 0 5
3600 2100 1200 2100 1200 1500 3600 1500 3600 2100
2 4 0 1 -1 0 1 0 20 0.000 0 0 7 0 0 5
7500 1500 5100 1500 5100 900 7500 900 7500 1500
2 4 0 1 -1 31 1 0 20 0.000 0 0 7 0 0 5
3600 3300 1200 3300 1200 2700 3600 2700 3600 3300
2 4 0 1 -1 8 1 0 20 0.000 0 0 7 0 0 5
3600 6000 1200 6000 1200 5400 3600 5400 3600 6000
2 4 0 1 -1 31 1 0 20 0.000 0 0 7 0 0 5
7500 3300 5100 3300 5100 2700 7500 2700 7500 3300
2 4 0 1 -1 8 1 0 20 0.000 0 0 7 0 0 5
3600 8400 1200 8400 1200 7800 3600 7800 3600 8400
2 4 0 1 -1 8 1 0 20 0.000 0 0 7 0 0 5
3600 9600 1200 9600 1200 9000 3600 9000 3600 9600
2 1 2 2 -1 7 0 0 -1 3.000 0 1 -1 1 1 2
0 0 2.00 80.00 150.00
0 0 2.00 80.00 150.00
4500 1425 5135 1194
2 1 2 2 -1 7 0 0 -1 4.000 0 1 -1 1 1 2
0 0 2.00 80.00 150.00
0 0 2.00 80.00 150.00
4725 2025 5160 1467
2 1 0 2 20 7 1 0 -1 0.000 0 0 -1 1 0 2
0 0 2.00 150.00 180.00
2400 2100 2400 2700
2 1 0 2 31 7 1 0 -1 0.000 0 0 -1 1 0 2
0 0 2.00 150.00 180.00
2400 3300 2400 4275
2 4 0 1 -1 8 1 0 20 0.000 0 0 7 0 0 5
3600 7200 1200 7200 1200 6600 3600 6600 3600 7200
2 4 0 1 -1 8 1 0 20 0.000 0 0 7 0 0 5
3600 10800 1200 10800 1200 10200 3600 10200 3600 10800
2 4 0 1 -1 8 1 0 20 0.000 0 0 7 0 0 5
3600 4800 1200 4800 1200 4200 3600 4200 3600 4800
2 1 1 2 32 7 1 0 -1 4.000 0 0 -1 1 0 2
0 0 2.00 150.00 180.00
2400 8400 2400 9000
2 1 1 2 32 7 1 0 -1 4.000 0 0 -1 1 0 2
0 0 2.00 150.00 180.00
2400 7200 2400 7800
2 1 1 2 32 7 1 0 -1 4.000 0 0 -1 1 0 2
0 0 2.00 150.00 180.00
2400 6000 2400 6600
2 1 1 2 32 7 1 0 -1 4.000 0 0 -1 1 0 2
0 0 2.00 150.00 180.00
2400 4800 2400 5400
2 1 1 2 32 7 1 0 -1 4.000 0 0 -1 1 0 2
0 0 2.00 150.00 180.00
3600 5700 5100 5700
2 1 0 2 25 7 0 0 -1 0.000 0 0 -1 1 0 2
0 0 2.00 150.00 180.50
2400 900 2400 1500
2 4 0 1 -1 8 1 0 20 0.000 0 0 7 0 0 5
7500 6000 5100 6000 5100 5400 7500 5400 7500 6000
2 4 0 1 33 33 3 0 20 0.000 0 0 40 0 0 5
8700 11100 300 11100 300 3600 8700 3600 8700 11100
2 1 0 2 29 7 0 0 -1 0.000 0 0 -1 1 1 2
0 0 2.00 150.00 180.00
0 0 2.00 150.00 180.00
3150 13050 3150 13650
2 1 0 2 29 7 0 0 -1 0.000 0 0 -1 1 1 2
0 0 2.00 150.00 180.00
0 0 2.00 150.00 180.00
1500 12450 1500 11850
2 4 0 1 -1 29 1 0 20 0.000 0 0 7 0 0 5
2700 13050 300 13050 300 12450 2700 12450 2700 13050
2 4 0 1 -1 29 1 0 20 0.000 0 0 7 0 0 5
6000 13050 3600 13050 3600 12450 6000 12450 6000 13050
2 4 0 1 -1 29 1 0 20 0.000 0 0 7 0 0 5
7500 14250 5100 14250 5100 13650 7500 13650 7500 14250
2 4 0 1 -1 29 1 0 20 0.000 0 0 7 0 0 5
4200 14250 1800 14250 1800 13650 4200 13650 4200 14250
2 1 0 2 29 7 0 0 -1 0.000 0 0 -1 1 1 2
0 0 2.00 150.00 180.00
0 0 2.00 150.00 180.00
4800 12450 4800 11850
2 1 0 2 29 7 0 0 -1 0.000 0 0 -1 1 1 2
0 0 2.00 150.00 180.00
0 0 2.00 150.00 180.00
6300 13050 6300 13650
2 4 0 1 -1 29 1 0 20 0.000 0 0 7 0 0 5
9300 13050 6600 13050 6600 12450 9300 12450 9300 13050
2 1 0 2 29 7 0 0 -1 0.000 0 0 -1 1 1 2
0 0 2.00 150.00 180.00
0 0 2.00 150.00 180.00
7950 11850 7950 12450
2 1 1 2 5 7 1 0 -1 4.000 0 0 -1 1 0 2
0 0 2.00 150.00 180.00
2400 6000 2400 6600
2 1 1 2 32 7 1 0 -1 4.000 0 0 -1 1 0 2
0 0 2.00 150.00 180.00
2400 9600 2400 10200
3 2 2 2 20 7 0 0 -1 6.000 1 1 0 5
0 0 2.00 150.00 180.00
2415 2140 3090 2440 5265 2515 6090 2590 6315 2740
0.000 -1.000 -1.000 -1.000 0.000
3 0 1 2 32 7 1 0 -1 4.500 0 1 0 7
0 0 2.00 150.00 150.00
7500 5700 8400 5400 8400 4500 7800 3900 3600 3900 3000 3900
2700 4200
0.000 1.000 1.000 1.000 1.000 1.000 0.000
3 0 1 2 32 7 0 0 -1 4.000 0 1 0 8
0 0 2.00 150.00 150.00
1125 10500 900 10350 675 9975 675 4350 900 3975 1350 3900
1800 3900 2100 4200
0.000 1.000 1.000 1.000 1.000 1.000 1.000 0.000
4 1 5 2 0 28 18 0.0000 4 285 870 4350 5625 utility\001
4 1 -1 0 0 16 18 0.0000 4 210 1455 2400 1950 Postmaster\001
4 1 -1 0 0 16 18 0.0000 4 270 1125 2400 3150 Postgres\001
4 1 -1 0 0 16 18 0.0000 4 270 1125 6300 3150 Postgres\001
4 1 7 0 0 16 18 0.0000 4 270 720 6300 1350 Libpq\001
4 1 -1 0 0 16 18 0.0000 4 210 615 2400 750 Main\001
4 1 7 0 0 16 18 0.0000 4 210 1815 2400 9450 Generate Plan\001
4 1 7 0 0 16 18 0.0000 4 270 1440 2400 5850 Traffic Cop\001
4 1 7 0 0 16 18 0.0000 4 210 1980 2400 8250 Generate Paths\001
4 1 5 2 0 28 18 0.0000 4 225 615 2400 9900 Plan\001
4 1 5 2 0 28 18 0.0000 4 285 1920 2400 8700 Optimal Path\001
4 1 5 2 0 28 18 0.0000 4 285 900 2400 6300 Query\001
4 1 7 0 0 16 18 0.0000 4 210 1680 2400 10650 Execute Plan\001
4 0 5 0 0 16 12 0.0000 4 210 2640 5250 6300 e.g. CREATE TABLE, COPY\001
4 1 5 0 0 16 12 0.0000 4 195 3540 2400 6525 SELECT, INSERT, UPDATE, DELETE\001
4 1 7 0 0 16 18 0.0000 4 270 1800 2400 7050 Rewrite Query\001
4 1 7 0 0 16 18 0.0000 4 210 2130 2400 4650 Parse Statement\001
4 1 7 0 0 16 18 0.0000 4 270 720 6300 5700 Utility\001
4 1 7 0 0 16 18 0.0000 4 210 1335 6300 6000 Command\001
4 1 -1 0 0 16 18 0.0000 4 270 2355 7950 12900 Storage Managers\001
4 1 -1 0 0 16 18 0.0000 4 270 1020 4800 12900 Catalog\001
4 1 -1 0 0 16 18 0.0000 4 210 915 1500 12900 Utilities\001
4 1 -1 0 0 16 18 0.0000 4 210 2085 3000 14100 Access Methods\001
4 1 -1 0 0 16 18 0.0000 4 210 1635 6300 14100 Nodes / Lists\001
src/tools/backend/index.html deleted 100644 → 0
View file @ 2042185b
<!-- src/tools/backend/index.html -->
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta name="generator"
content="HTML Tidy for BSD/OS (vers 1st July 2002), see www.w3.org" />
<title>How PostgreSQL Processes a Query</title>
</head>
<body bgcolor="#FFFFFF" text="#000000" link="#FF0000"
vlink="#A00000" alink="#0000FF">
<h1>How PostgreSQL Processes a Query</h1>
<h2>by Bruce Momjian</h2>
<center>
<h3><i>Click on an item</i> to see more detail or look at the full
<a href="backend_dirs.html">index.</a></h3>
<p><img src="flow.gif" usemap="#flowmap" alt="flowchart" />
<map name="flowmap" id="flowmap">
<area coords="45, 0, 175, 30" href="backend_dirs.html#main" alt="main" />
<area coords="255, 35, 380, 65" href="backend_dirs.html#libpq" alt="libpq" />
<area coords="45, 65, 175, 95" href="backend_dirs.html#postmaster" alt="postmaster" />
<area coords="45, 130, 175, 160" href="backend_dirs.html#tcop" alt="tcop" />
<area coords="250, 130, 380, 160" href="backend_dirs.html#tcop" alt="tcop" />
<area coords="45, 205, 175, 240" href="backend_dirs.html#parser" alt="parser" />
<area coords="45, 270, 175, 300" href="backend_dirs.html#tcop" alt="tcop" />
<area coords="255, 270, 380, 300" href="backend_dirs.html#commands" alt="commands" />
<area coords="45, 335, 175, 365" href="backend_dirs.html#rewrite" alt="rewrite" />
<area coords="45, 400, 175, 430" href="backend_dirs.html#optimizer_path" alt="path" />
<area coords="45, 460, 175, 490" href="backend_dirs.html#optimizer_plan" alt="plan" />
<area coords="45, 525, 175, 555" href="backend_dirs.html#executor" alt="executor" />
<area coords="0, 640, 130, 675" href="backend_dirs.html#utils" alt="utils" />
<area coords="175, 640, 300, 675" href="backend_dirs.html#catalog" alt="catalog" />
<area coords="330, 640, 475, 675" href="backend_dirs.html#storage" alt="storage" />
<area coords="75, 700, 210, 735" href="backend_dirs.html#access" alt="access" />
<area coords="255, 705, 380, 735" href="backend_dirs.html#nodes" alt="nodes" />
</map>
</center>
<br />
<p>A query comes to the backend via data packets arriving through
TCP/IP or Unix Domain sockets. It is loaded into a string, and
passed to the <a href="../../backend/parser">parser,</a> where the
lexical scanner, <a href="../../backend/parser/scan.l">scan.l,</a>
breaks the query up into tokens(words). The parser uses <a
href="../../backend/parser/gram.y">gram.y</a> and the tokens to
identify the query type, and load the proper query-specific
structure, like <a
href="../../include/nodes/parsenodes.h">CreateStmt</a> or <a
href="../../include/nodes/parsenodes.h">SelectStmt.</a></p>
<p>The statement is then identified as complex (<i>SELECT / INSERT /
UPDATE / DELETE</i>) or a simple, e.g <i> CREATE USER, ANALYZE, </i>,
etc. Simple utility commands are processed by statement-specific
functions in <a href="../../backend/commands">backend/commands.</a>
Complex statements require more handling.</p>
<p>The parser takes a complex query, and creates a <a
href="../../include/nodes/parsenodes.h">Query</a> structure that
contains all the elements used by complex queries. Query.qual holds
the <i>WHERE</i> clause qualification, which is filled in by <a
href="../../backend/parser/parse_clause.c">transformWhereClause().</a>
Each table referenced in the query is represented by a <a
href="../../include/nodes/parsenodes.h">RangeTableEntry,</a> and
they are linked together to form the <i>range table</i> of the
query, which is generated by <a
href="../../backend/parser/parse_clause.c">transformFromClause().</a>
Query.rtable holds the query's range table.</p>
<p>Certain queries, like <i>SELECT,</i> return columns of data.
Other queries, like <i>INSERT</i> and <i>UPDATE,</i> specify the
columns modified by the query. These column references are
converted to <a
href="../../include/nodes/primnodes.h">TargetEntry</a> entries,
which are linked together to make up the <i>target list</i> of the
query. The target list is stored in Query.targetList, which is
generated by <a
href="../../backend/parser/parse_target.c">transformTargetList().</a></p>
<p>Other query elements, like aggregates(<i>SUM()</i>), <i>GROUP
BY,</i> and <i>ORDER BY</i> are also stored in their own Query
fields.</p>
<p>The next step is for the Query to be modified by any
<i>VIEWS</i> or <i>RULES</i> that may apply to the query. This is
performed by the <a href="../../backend/rewrite">rewrite</a>
system.</p>
<p>The <a href="../../backend/optimizer">optimizer</a> takes the
Query structure and generates an optimal <a
href="../../include/nodes/plannodes.h">Plan,</a> which contains the
operations to be performed to execute the query. The <a
href="../../backend/optimizer/path">path</a> module determines the
best table join order and join type of each table in the
RangeTable, using Query.qual(<i>WHERE</i> clause) to consider
optimal index usage.</p>
<p>The Plan is then passed to the <a
href="../../backend/executor">executor</a> for execution, and the
result returned to the client. The Plan is actually as set of nodes,
arranged in a tree structure with a top-level node, and various
sub-nodes as children.</p>
<p>There are many other modules that support this basic
functionality. They can be accessed by clicking on the
flowchart.</p>
<hr />
<p>Another area of interest is the shared memory area, which
contains data accessible to all backends. It has recently used
data/index blocks, locks, backend process information, and lookup
tables for these structures:</p>
<ul>
<li>ShmemIndex - lookup shared memory addresses using structure
names</li>
<li><a href="../../include/storage/buf_internals.h">Buffer
Descriptor</a> - control header for buffer cache block</li>
<li><a href="../../include/storage/buf_internals.h">Buffer
Block</a> - data/index buffer cache block</li>
<li>Shared Buffer Lookup Table - lookup of buffer cache block
addresses using table name and block number( <a
href="../../include/storage/buf_internals.h">BufferTag</a>)</li>
<li>Lock Manager Tables (lock hash) - the <a
href="../../include/storage/lock.h">LOCK</a> structure, looked up
using a <a href="../../include/storage/lock.h">LOCKTAG</a>.
A LOCK structure exists for each lockable object that is currently
locked by any backend. Also, there is a subsidiary <a
href="../../include/storage/lock.h">PROCLOCK</a> structure for each
backend currently interested in a given LOCK</li>
<li><a href="../../include/storage/proc.h">PGPROC Structures</a> -
information about each backend, including locks held/waiting</li>
</ul>
<p>Each data structure is created by calling <a
href="../../backend/storage/ipc/shmem.c">ShmemInitStruct(),</a> and
the lookups are created by <a
href="../../backend/storage/ipc/shmem.c">ShmemInitHash().</a></p>
<hr />
<small>Maintainer: Bruce Momjian (<a
href="mailto:pgman@candle.pha.pa.us">pgman@candle.pha.pa.us</a>)<br />
Last updated: Fri May 6 14:22:27 EDT 2005</small>
</body>
</html>
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment