From e38c920dba59a39322a865997e4d33715a6e38a7 Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Wed, 10 Aug 2005 19:30:05 +0000 Subject: [PATCH] Add new FAQ information. Martijn van Oosterhout --- doc/FAQ | 27 ++++++++++++++++++++++++++- doc/src/FAQ/FAQ.html | 44 ++++++++++++++++++++++++++++++++++++++------ 2 files changed, 64 insertions(+), 7 deletions(-) diff --git a/doc/FAQ b/doc/FAQ index d7e2d5ea59..e1c3cf1999 100644 --- a/doc/FAQ +++ b/doc/FAQ @@ -1,7 +1,7 @@ Frequently Asked Questions (FAQ) for PostgreSQL - Last updated: Fri Jul 29 10:05:09 EDT 2005 + Last updated: Wed Aug 10 15:29:42 EDT 2005 Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) @@ -79,6 +79,7 @@ 4.19) Why do I get "relation with OID ##### does not exist" errors when accessing temporary tables in PL/PgSQL functions? 4.20) What replication solutions are available? + 4.21) Why are my table and column names not recognized in my query? _________________________________________________________________ General Questions @@ -471,6 +472,12 @@ The maximum table size and maximum number of columns can be quadrupled by increasing the default block size to 32k. + One limitation is that indexes can not be created on columns longer + than about 2,000 characters. Fortunately, such indexes are rarely + needed. Uniqueness is best guaranteed using another column that is an + MD5 hash of the long column, and full text indexing allows for + searching of words within the column. + 4.5) How much database disk space is required to store data from a typical text file? @@ -578,6 +585,11 @@ expresssion index, it will be used: CREATE INDEX tabindex ON tab (lower(col)); + If the above index is created as UNIQUE, though the column can store + upper and lowercase characters, it can not have identical values that + differ only in case. To force a particular case to be stored in the + column, use a CHECK constraint or a trigger. + 4.9) In a query, how do I detect if a field is NULL? How can I sort on whether a field is NULL or not? @@ -776,3 +788,16 @@ There are also commercial and hardware-based replication solutions available supporting a variety of replication models. + + 4.20) Why are my table and column names not recognized in my query? + + The most common cause is the use of double-quotes around table or + column names during table creation. When double-quotes are used, table + and column names (called identifiers) are stored case-sensitive, + meaning you must use double-quotes when referencing the names in a + query. Some interfaces, like pgAdmin, automatically double-quote + identifiers during table creation. So, for identifiers to be + recognized, you must either: + * Avoid double-quoting identifiers when creating tables + * Use only lowercase characters in identifiers + * Double-quote identifiers when referencing them in queries diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html index 71e659db94..07dd956e2e 100644 --- a/doc/src/FAQ/FAQ.html +++ b/doc/src/FAQ/FAQ.html @@ -10,7 +10,7 @@ alink="#0000ff">

Frequently Asked Questions (FAQ) for PostgreSQL

-

Last updated: Mon May 30 09:11:03 EDT 2005

+

Last updated: Wed Aug 10 15:29:42 EDT 2005

Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) @@ -26,7 +26,7 @@

General Questions

- 1.1) What is PostgreSQL? How is it pronounced?
+ 1.1) What is PostgreSQL? How is it pronounced?
1.2) What is the copyright of PostgreSQL?
1.3) What platforms does PostgreSQL support?
1.4) Where can I get PostgreSQL?
@@ -116,7 +116,9 @@ does not exist" errors when accessing temporary tables in PL/PgSQL functions?
4.20) What replication solutions are available?
- + 4.21) Why are my table and column names not + recognized in my query?
+
@@ -124,8 +126,10 @@

1.1) What is PostgreSQL? How is it pronounced?

-

PostgreSQL is pronounced Post-Gres-Q-L, also called just - Postgres.

+

PostgreSQL is pronounced Post-Gres-Q-L, and is also sometimes + referred to as just Postgres. An audio file is available in + MP3 format for + those would like to hear the pronunciation.

PostgreSQL is an object-relational database system that has the features of traditional commercial database systems with @@ -613,6 +617,12 @@ table?unlimited

The maximum table size and maximum number of columns can be quadrupled by increasing the default block size to 32k.

+

One limitation is that indexes can not be created on columns + longer than about 2,000 characters. Fortunately, such indexes are + rarely needed. Uniqueness is best guaranteed using another column + that is an MD5 hash of the long column, and full text indexing + allows for searching of words within the column.

+

4.5) How much database disk space is required to store data from a typical text file?

@@ -740,7 +750,12 @@ table?unlimited 
     CREATE INDEX tabindex ON tab (lower(col));
- +

If the above index is created as UNIQUE, though + the column can store upper and lowercase characters, it can not have + identical values that differ only in case. To force a particular + case to be stored in the column, use a CHECK + constraint or a trigger.

+

4.9) In a query, how do I detect if a field is NULL? How can I sort on whether a field is NULL or not?

@@ -1000,5 +1015,22 @@ length

There are also commercial and hardware-based replication solutions available supporting a variety of replication models.

+ +

4.20) Why are my table and column names not + recognized in my query?

+ +

The most common cause is the use of double-quotes around table or + column names during table creation. When double-quotes are used, + table and column names (called identifiers) are stored case-sensitive, meaning you must use + double-quotes when referencing the names in a query. Some interfaces, + like pgAdmin, automatically double-quote identifiers during table + creation. So, for identifiers to be recognized, you must either: +