Commit 37df2996 authored by Pierangelo Masarati's avatar Pierangelo Masarati
Browse files

note workaround for ITS#4785; cleanup

parent bd33fc86
......@@ -26,7 +26,7 @@ You can take a look at
(OpenLDAP FAQ-O-Matic/General LDAP FAQ/Directories vs. conventional
databases) to find out more on this point.
.LP
The idea (detailed below) is to use some metainformation to translate
The idea (detailed below) is to use some meta-information to translate
LDAP queries to SQL queries, leaving relational schema untouched, so
that old applications can continue using it without any
modifications.
......@@ -34,7 +34,7 @@ This allows SQL and LDAP applications to inter-operate without
replication, and exchange data as needed.
.LP
The SQL backend is designed to be tunable to virtually any relational
schema without having to change source (through that metainformation
schema without having to change source (through that meta-information
mentioned).
Also, it uses ODBC to connect to RDBMSes, and is highly configurable
for SQL dialects RDBMSes may use, so it may be used for integration
......@@ -107,7 +107,7 @@ suffix, and the scope is subtree; rather collect all entries.
.RE
.SH STATEMENT CONFIGURATION
These options specify SQL query templates for loading schema mapping
metainformation, adding and deleting entries to ldap_entries, etc.
meta-information, adding and deleting entries to ldap_entries, etc.
All these and subtree_cond should have the given default values.
For the current value it is recommended to look at the sources,
or in the log output when slapd starts with "-d 5" or greater.
......@@ -520,7 +520,7 @@ not very narrow ;) If anyone needs support for different types for
keys - he may want to write a patch, and submit it to OpenLDAP ITS,
then I'll include it.
.LP
Also, several people complained that they don't really need very
Also, several users complained that they don't really need very
structured trees, and they don't want to update one more table every
time they add or delete an instance in the relational schema.
Those people can use a view instead of a real table for ldap_entries, something
......@@ -551,8 +551,8 @@ and the baseObject cannot be created; in this case, see the
directive for a possible workaround.
.LP
.SH Typical SQL backend operation
Having metainformation loaded, the SQL backend uses these tables to
.SH TYPICAL SQL BACKEND OPERATION
Having meta-information loaded, the SQL backend uses these tables to
determine a set of primary keys of candidates (depending on search
scope and filter).
It tries to do it for each objectclass registered in ldap_objclasses.
......@@ -592,7 +592,7 @@ into the most relaxed SQL condition to filter candidates), and send it to
the user.
.LP
ADD, DELETE, MODIFY and MODRDN operations are also performed on per-attribute
metainformation (add_proc etc.).
meta-information (add_proc etc.).
In those fields one can specify an SQL statement or stored procedure
call which can add, or delete given values of a given attribute, using
the given entry keyval (see examples -- mostly PostgreSQL, ORACLE and MSSQL
......@@ -605,17 +605,16 @@ Please see samples to find out what are the parameters passed, and other
information on this matter - they are self-explanatory for those familiar
with the concepts expressed above.
.LP
.SH Common techniques (referrals, multiclassing etc.)
First of all, let's remember that among other major differences to the
complete LDAP data model, the concept above does not directly support
such things as multiple objectclasses per entry, and referrals.
.SH COMMON TECHNIQUES
First of all, let's recall that among other major differences to the
complete LDAP data model, the above illustrated concept does not directly
support such features as multiple objectclasses per entry, and referrals.
Fortunately, they are easy to adopt in this scheme.
The SQL backend suggests one more table being added to the schema:
The SQL backend requires that one more table is added to the schema:
ldap_entry_objectclasses(entry_id,oc_name).
.LP
The first contains any number of objectclass names that corresponding
entries will be found by, in addition to that mentioned in
mapping.
That table contains any number of objectclass names that corresponding
entries will possess, in addition to that mentioned in mapping.
The SQL backend automatically adds attribute mapping for the "objectclass"
attribute to each objectclass mapping that loads values from this table.
So, you may, for instance, have a mapping for inetOrgPerson, and use it
......@@ -635,7 +634,7 @@ The use of the naming attribute usually requires to add
an "extensibleObject" value to ldap_entry_objclasses.
.LP
.SH Caveats
.SH CAVEATS
As previously stated, this backend should not be considered
a replacement of other data storage backends, but rather a gateway
to existing RDBMS storages that need to be published in LDAP form.
......@@ -652,11 +651,22 @@ If you need to find all the leaf entries, please use
instead.
.LP
A directoryString value of the form "__First___Last_"
(where underscores should be replaced by spaces) corresponds
(where underscores mean spaces, ASCII 0x20 char) corresponds
to its prettified counterpart "First_Last"; this is not currently
honored by back-sql if non-prettified data is written via RDBMS;
when non-prettified data is written thru back-sql, the prettified
values are actually used instead.
.LP
.SH BUGS
When the
.B ldap_entry_objclasses
table is empty, filters on the
.B objectClass
attribute erroneously result in no candidates.
A workaround consists in adding at least one row to that table,
no matter if valid or not.
.LP
.SH PROXY CACHE OVERLAY
The proxy cache overlay
......
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