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<chapter id="advanced">

<para>

Let's create two classes. The capitals class contains

state capitalswhich are also cities. Naturally, the

state capitalsthat are also cities. Naturally, the

capitals class should inherit from cities.

<programlisting>

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<chapter id="overview">

the parser as input and steps recursively through it. If

a <literal>SelectStmt</literal> node is found, it is transformed

to a <literal>Query</literal>

nodewhich will be the top most node of the new data structure. Figure

nodethat will be the top most node of the new data structure. Figure

\ref{transformed} shows the transformed data structure (the part

for the transformed <firstterm>where clause</firstterm> is given in figure

\ref{transformed_where} because there was not enough space to show all

created containing the relation name, the <firstterm>alias name</firstterm> and

the <firstterm>relation id</firstterm>. From now on the relation ids are used to

refer to the <firstterm>relations</firstterm> given in the query. All <abbrev>RTE</abbrev> nodes

are collected in the <firstterm>range table entry list</firstterm>which is connected

are collected in the <firstterm>range table entry list</firstterm>that is connected

to the field <literal>rtable</literal> of the <literal>Query</literal> node. If a name of a

relation that is not known to the system is detected in the query an

error will be returned and the query processing will be aborted.

</para>

<para>

The top node of the plan is a <literal>MergeJoin</literal> nodewhich has two

The top node of the plan is a <literal>MergeJoin</literal> nodethat has two

successors, one attached to the field <literal>lefttree</literal> and the second

attached to the field <literal>righttree</literal>. Each of the subnodes represents

one relation of the join. As mentioned above a merge sort

A check is made that every attribute grouped for appears only without

an {\it aggregate function} in the {\it targetlist} and that every

attributewhich appears without an {\it aggregate function} in the

attributethat appears without an {\it aggregate function} in the

{\it targetlist} is grouped for.

%

transformation of the {\it operator tree} for the {\it where clause}. This

is possible because both trees are built up by the same grammar rules

of the {\it parser} and are therefore compatible. Additional checks

which make sure that the {\it having clause} involves at least one

that make sure that the {\it having clause} involves at least one

{\it aggregate function} etc. are performed at a later point in time

in the {\it planner/optimizer} stage. \\

\\

functions. Every added source line will be marked by a {\tt '+'} at the

beginning of the line and every changed source line will be marked by

a {\tt '!'} throughout the following code listings. Whenever a part of

the codewhich is not relevant at the moment is skipped, three

the codethat is not relevant at the moment is skipped, three

vertical dots are inserted instead.

%

\pagebreak

Unfortunately this is not the only thing to do. Remember from section

\ref{aggregates} {\it How Aggregate Functions are Implemented} that

the {\it targetlist} is searched for {\it aggregate functions}which

the {\it targetlist} is searched for {\it aggregate functions}that

are appended to a list that will be attached to the field {\tt aggs}

of the {\tt AGG} node. This was sufficient as long as {\it aggregate

functions} have only been allowed to appear within the {\it

%

\end{itemize}

%

Here is a part of the grammarwhich is responsible for {\tt select}

Here is a part of the grammarthat is responsible for {\tt select}

statements having the code building up the data structures inserted:

%

\pagebreak

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Transcribed from the original bki.man.5 documentation

- Thomas Lockhart 1998-08-03

<para>

Commands are composed of a command name followed by space separated

arguments. Arguments to a commandwhich begin with a "$" are

arguments. Arguments to a commandthat begin with a "$" are

treated specially. If "$$" are the first two characters, then

the first "$" is ignored and the argument is then processed

normally. If the "$" is followed by space, then it is treated

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<chapter id="catalogs">

stored in the attribute is the OID of a tuple in the

<structname>pg_proc</structname> catalog. The

<structname>pg_proc</structname> tuple contains the query

stringwhich defines this set - i.e., the query to run to get

stringthat defines this set - i.e., the query to run to get

the set. So the <structfield>atttypid</structfield> (see

above) refers to the type returned by this query, but the

actual length of this attribute is the length (size) of an

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CVS code repository

Thomas Lockhart

-->

</programlisting>

and if you want to build a static binary to move to systems

which may not have Modula-3 installed, try:

that may not have Modula-3 installed, try:

<programlisting>

# make M3FLAGS="-DNOGUI -DSTATIC"

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<chapter id="datatype">

of <acronym>SQL92</acronym> are also supported.

Although we strive for <acronym>SQL92</acronym> compliance,

there are some aspects of the standard

which are ill considered and which should not live through subsequent standards.

that are ill considered and which should not live through subsequent standards.

<productname>Postgres</productname> will not make great efforts to

conform to these features; however, these tend to apply in little-used

or obsure cases, and a typical user is not likely to run into them.

<para>

This type is defined by SQL92, but the definition exhibits

fundamental deficiencieswhich renders the type nearly useless. In

fundamental deficienciesthat render the type nearly useless. In

most cases, a combination of <type>date</type>,

<type>time</type>, and <type>timestamp</type>

should provide a complete range of date/time functionality

1999-01-08 04:05:06 -8:00

</programlisting>

is a valid <type>timestamp</type> value, which is <acronym>ISO</acronym>-compliant.

is a valid <type>timestamp</type> value that is <acronym>ISO</acronym>-compliant.

In addition, the wide-spread format

<programlisting>

<para>

To address these difficulties, we recommend using date/time

typeswhich contain both date and time when using time zones. We

typesthat contain both date and time when using time zones. We

recommend <emphasis>not</emphasis> using the SQL92 type TIME

WITH TIME ZONE (though it is supported by

<productname>Postgres</productname> for legacy applications and

<title>Box</title>

<para>

Boxes are represented by pairs of pointswhich are opposite

Boxes are represented by pairs of pointsthat are opposite

corners of the box.

</para>

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<appendix label="DG2" id="docguide">

<title>Documentation</title>

<para>

<productname>JadeTeX</productname> does not at the time of

writing come with much of an installation guide, but there is a

<filename>makefile</filename>which shows what is needed. It

<filename>makefile</filename>that shows what is needed. It

also includes a directory <filename>cooked</filename>, wherein

you'll find some of the macro packages it needs, but not all, and

not complete -- at least last we looked.

Not all documents have figures.

You can grep the <acronym>SGML</acronym> source files for

the string "<literal>graphic</literal>" to identify those parts of the

documentationwhich may have figures. A few figures are replicated in

documentationthat may have figures. A few figures are replicated in

various parts of the documentation.

</para>

</note>

<step performance="required">

<para>

Lop off the parts of the documentwhich are not needed.

Lop off the parts of the documentthat are not needed.

</para>

<para>

<para>

Indexes are commonly used to enhance database

performance. They should be defined on table columns (or class

attributes)which are used as qualifications in repetitive queries.

attributes)that are used as qualifications in repetitive queries.

Inappropriate use will result in slower performance, since update

and insertion times are increased in the presence of indices.

</para>

<para>

Thus, you may query a table by any combination of its columns, despite the

fact that you don't have an index on these columns. The indexes are merely

an implementational aidwhich each <acronym>RDBMS</acronym> offers

an implementational aidthat each <acronym>RDBMS</acronym> offers

you, in order to cause

commonly used queries to be done more efficiently.

Some <acronym>RDBMS</acronym> may give you

</para>

<para>

So, if you want to use a combination of fieldswhich is not unique as a

So, if you want to use a combination of fieldsthat is not unique as a

secondary key, you really don't have to specify anything - just start

retrieving by that combination! However, if you want to make the retrieval

efficient, you'll have to resort to the means your

<acronym>RDBMS</acronym> provider gives you

- be it an index, my imaginary MEMSTORE command, or an intelligent

<acronym>RDBMS</acronym>

which creates indices without your knowledge based on the fact that you have

that creates indices without your knowledge based on the fact that you have

sent it many queries based on a specific combination of keys... (It learns

from experience).

</para>

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<chapter id="installation">

<title><![%flattext-install-include[<productname>PostgreSQL</>]]> Installation Instructions</title>

</para>

<para>

On systemswhich have <productname>PostgreSQL</> started at boot time, there is

On systemsthat have <productname>PostgreSQL</> started at boot time, there is

probably a start-up file that will accomplish the same thing. For

example, on a Red Hat Linux system one might find that

<screen>

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<chapter id="jdbc">

public class PGpath extends PGobject implements Serializable,

Cloneable

This implements a path (amultiple segmented line, which may be

This implements a path (amultiply segmented line, which may be

closed)

Variables