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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 11:11:40 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 11:11:40 +0000 |
commit | 7731832751ab9f3c6ddeb66f186d3d7fa1934a6d (patch) | |
tree | e91015872543a59be2aad26c2fea02e41b57005d /doc/man/man5/slapd-sql.5 | |
parent | Initial commit. (diff) | |
download | openldap-upstream/2.4.57+dfsg.tar.xz openldap-upstream/2.4.57+dfsg.zip |
Adding upstream version 2.4.57+dfsg.upstream/2.4.57+dfsgupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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-rw-r--r-- | doc/man/man5/slapd-sql.5 | 699 |
1 files changed, 699 insertions, 0 deletions
diff --git a/doc/man/man5/slapd-sql.5 b/doc/man/man5/slapd-sql.5 new file mode 100644 index 0000000..8492553 --- /dev/null +++ b/doc/man/man5/slapd-sql.5 @@ -0,0 +1,699 @@ +.TH SLAPD-SQL 5 "RELEASEDATE" "OpenLDAP LDVERSION" +.\" $OpenLDAP$ +.SH NAME +slapd\-sql \- SQL backend to slapd +.SH SYNOPSIS +ETCDIR/slapd.conf +.SH DESCRIPTION +The primary purpose of this +.BR slapd (8) +backend is to PRESENT information stored in some RDBMS as an LDAP subtree +without any programming (some SQL and maybe stored procedures can't be +considered programming, anyway ;). +.LP +That is, for example, when you (some ISP) have account information you +use in an RDBMS, and want to use modern solutions that expect such +information in LDAP (to authenticate users, make email lookups etc.). +Or you want to synchronize or distribute information between different +sites/applications that use RDBMSes and/or LDAP. +Or whatever else... +.LP +It is NOT designed as a general-purpose backend that uses RDBMS instead +of BerkeleyDB (as the standard BDB backend does), though it can be +used as such with several limitations. +You can take a look at +.B http://www.openldap.org/faq/index.cgi?file=378 +(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 meta-information to translate +LDAP queries to SQL queries, leaving relational schema untouched, so +that old applications can continue using it without any +modifications. +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 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 +and distribution of data on different RDBMSes, OSes, hosts etc., in +other words, in highly heterogeneous environment. +.LP +This backend is \fIexperimental\fP. +.SH CONFIGURATION +These +.B slapd.conf +options apply to the SQL backend database, which means that +they must follow a "database sql" line and come before any +subsequent "backend" or "database" lines. +Other database options not specific to this backend are described +in the +.BR slapd.conf (5) +manual page. +.SH DATA SOURCE CONFIGURATION + +.TP +.B dbname <datasource name> +The name of the ODBC datasource to use. +.LP +.B dbhost <hostname> +.br +.B dbpasswd <password> +.br +.B dbuser <username> +.RS +The three above options are generally unneeded, because this information +is taken from the datasource specified by the +.B dbname +directive. +They allow to override datasource settings. +Also, several RDBMS' drivers tend to require explicit passing of user/password, +even if those are given in datasource (Note: +.B dbhost +is currently ignored). +.RE +.SH SCOPING CONFIGURATION +These options specify SQL query templates for scoping searches. + +.TP +.B subtree_cond <SQL expression> +Specifies a where-clause template used to form a subtree search condition +(dn="(.+,)?<dn>$"). +It may differ from one SQL dialect to another (see samples). +By default, it is constructed based on the knowledge about +how to normalize DN values (e.g. +\fB"<upper_func>(ldap_entries.dn) LIKE CONCAT('%',?)"\fP); +see \fBupper_func\fP, \fBupper_needs_cast\fP, \fBconcat_pattern\fP +and \fBstrcast_func\fP in "HELPER CONFIGURATION" for details. + +.TP +.B children_cond <SQL expression> +Specifies a where-clause template used to form a children search condition +(dn=".+,<dn>$"). +It may differ from one SQL dialect to another (see samples). +By default, it is constructed based on the knowledge about +how to normalize DN values (e.g. +\fB"<upper_func>(ldap_entries.dn) LIKE CONCAT('%,',?)"\fP); +see \fBupper_func\fP, \fBupper_needs_cast\fP, \fBconcat_pattern\fP +and \fBstrcast_func\fP in "HELPER CONFIGURATION" for details. + +.TP +.B use_subtree_shortcut { YES | no } +Do not use the subtree condition when the searchBase is the database +suffix, and the scope is subtree; rather collect all entries. + +.RE +.SH STATEMENT CONFIGURATION +These options specify SQL query templates for loading schema mapping +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. +Note that the parameter number and order must not be changed. + +.TP +.B oc_query <SQL expression> +The query that is used to collect the objectClass mapping data +from table \fIldap_oc_mappings\fP; see "METAINFORMATION USED" for details. +The default is +\fB"SELECT id, name, keytbl, keycol, create_proc, delete_proc, expect_return +FROM ldap_oc_mappings"\fP. + +.TP +.B at_query <SQL expression> +The query that is used to collect the attributeType mapping data +from table \fIldap_attr_mappings\fP; see "METAINFORMATION USED" for details. +The default is +\fB"SELECT name, sel_expr, from_tbls, join_where, add_proc, delete_proc, +param_order, expect_return FROM ldap_attr_mappings WHERE oc_map_id=?"\fP. + +.TP +.B id_query <SQL expression> +The query that is used to map a DN to an entry +in table \fIldap_entries\fP; see "METAINFORMATION USED" for details. +The default is +\fB"SELECT id,keyval,oc_map_id,dn FROM ldap_entries WHERE <DN match expr>"\fP, +where \fB<DN match expr>\fP is constructed based on the knowledge about +how to normalize DN values (e.g. \fB"dn=?"\fP if no means to uppercase +strings are available; typically, \fB"<upper_func>(dn)=?"\fP is used); +see \fBupper_func\fP, \fBupper_needs_cast\fP, \fBconcat_pattern\fP +and \fBstrcast_func\fP in "HELPER CONFIGURATION" for details. + +.TP +.B insentry_stmt <SQL expression> +The statement that is used to insert a new entry +in table \fIldap_entries\fP; see "METAINFORMATION USED" for details. +The default is +\fB"INSERT INTO ldap_entries (dn, oc_map_id, parent, keyval) VALUES +(?, ?, ?, ?)"\fP. + +.TP +.B delentry_stmt <SQL expression> +The statement that is used to delete an existing entry +from table \fIldap_entries\fP; see "METAINFORMATION USED" for details. +The default is +\fB"DELETE FROM ldap_entries WHERE id=?"\fP. + +.TP +.B delobjclasses_stmt <SQL expression> +The statement that is used to delete an existing entry's ID +from table \fIldap_objclasses\fP; see "METAINFORMATION USED" for details. +The default is +\fB"DELETE FROM ldap_entry_objclasses WHERE entry_id=?"\fP. + +.RE +.SH HELPER CONFIGURATION +These statements are used to modify the default behavior of the backend +according to issues of the dialect of the RDBMS. +The first options essentially refer to string and DN normalization +when building filters. +LDAP normalization is more than upper- (or lower-)casing everything; +however, as a reasonable trade-off, for case-sensitive RDBMSes the backend +can be instructed to uppercase strings and DNs by providing +the \fBupper_func\fP directive. +Some RDBMSes, to use functions on arbitrary data types, e.g. string +constants, requires a cast, which is triggered +by the \fBupper_needs_cast\fP directive. +If required, a string cast function can be provided as well, +by using the \fBstrcast_func\fP directive. +Finally, a custom string concatenation pattern may be required; +it is provided by the \fBconcat_pattern\fP directive. + +.TP +.B upper_func <SQL function name> +Specifies the name of a function that converts a given value to uppercase. +This is used for case insensitive matching when the RDBMS is case sensitive. +It may differ from one SQL dialect to another (e.g. \fBUCASE\fP, \fBUPPER\fP +or whatever; see samples). By default, none is used, i.e. strings are not +uppercased, so matches may be case sensitive. + +.TP +.B upper_needs_cast { NO | yes } +Set this directive to +.B yes +if +.B upper_func +needs an explicit cast when applied to literal strings. +A cast in the form +.B CAST (<arg> AS VARCHAR(<max DN length>)) +is used, where +.B <max DN length> +is builtin in back-sql; see macro +.B BACKSQL_MAX_DN_LEN +(currently 255; note that slapd's builtin limit, in macro +.BR SLAP_LDAPDN_MAXLEN , +is set to 8192). +This is \fIexperimental\fP and may change in future releases. + +.TP +.B strcast_func <SQL function name> +Specifies the name of a function that converts a given value to a string +for appropriate ordering. This is used in "SELECT DISTINCT" statements +for strongly typed RDBMSes with little implicit casting (like PostgreSQL), +when a literal string is specified. +This is \fIexperimental\fP and may change in future releases. + +.TP +.B concat_pattern <pattern> +This statement defines the +.B pattern +that is used to concatenate strings. The +.B pattern +MUST contain two question marks, '?', that will be replaced +by the two strings that must be concatenated. The default value is +.BR "CONCAT(?,?)"; +a form that is known to be highly portable (IBM db2, PostgreSQL) is +.BR "?||?", +but an explicit cast may be required when operating on literal strings: +.BR "CAST(?||? AS VARCHAR(<length>))". +On some RDBMSes (IBM db2, MSSQL) the form +.B "?+?" +is known to work as well. +Carefully check the documentation of your RDBMS or stay with the examples +for supported ones. +This is \fIexperimental\fP and may change in future releases. + +.TP +.B aliasing_keyword <string> +Define the aliasing keyword. Some RDBMSes use the word "\fIAS\fP" +(the default), others don't use any. + +.TP +.B aliasing_quote <string> +Define the quoting char of the aliasing keyword. Some RDBMSes +don't require any (the default), others may require single +or double quotes. + +.TP +.B has_ldapinfo_dn_ru { NO | yes } +Explicitly inform the backend whether the dn_ru column +(DN in reverse uppercased form) is present in table \fIldap_entries\fP. +Overrides automatic check (this is required, for instance, +by PostgreSQL/unixODBC). +This is \fIexperimental\fP and may change in future releases. + +.TP +.B fail_if_no_mapping { NO | yes } +When set to +.B yes +it forces \fIattribute\fP write operations to fail if no appropriate +mapping between LDAP attributes and SQL data is available. +The default behavior is to ignore those changes that cannot be mapped. +It has no impact on objectClass mapping, i.e. if the +.I structuralObjectClass +of an entry cannot be mapped to SQL by looking up its name +in ldap_oc_mappings, an +.I add +operation will fail regardless of the +.B fail_if_no_mapping +switch; see section "METAINFORMATION USED" for details. +This is \fIexperimental\fP and may change in future releases. + +.TP +.B allow_orphans { NO | yes } +When set to +.B yes +orphaned entries (i.e. without the parent entry in the database) +can be added. This option should be used with care, possibly +in conjunction with some special rule on the RDBMS side that +dynamically creates the missing parent. + +.TP +.B baseObject [ <filename> ] +Instructs the database to create and manage an in-memory baseObject +entry instead of looking for one in the RDBMS. +If the (optional) +.B <filename> +argument is given, the entry is read from that file in +.BR LDIF (5) +format; otherwise, an entry with objectClass \fBextensibleObject\fP +is created based on the contents of the RDN of the \fIbaseObject\fP. +This is particularly useful when \fIldap_entries\fP +information is stored in a view rather than in a table, and +.B union +is not supported for views, so that the view can only specify +one rule to compute the entry structure for one objectClass. +This topic is discussed further in section "METAINFORMATION USED". +This is \fIexperimental\fP and may change in future releases. + +.TP +.B create_needs_select { NO | yes } +Instructs the database whether or not entry creation +in table \fIldap_entries\fP needs a subsequent select to collect +the automatically assigned ID, instead of being returned +by a stored procedure. + +.LP +.B fetch_attrs <attrlist> +.br +.B fetch_all_attrs { NO | yes } +.RS +The first statement allows one to provide a list of attributes that +must always be fetched in addition to those requested by any specific +operation, because they are required for the proper usage of the +backend. For instance, all attributes used in ACLs should be listed +here. The second statement is a shortcut to require all attributes +to be always loaded. Note that the dynamically generated attributes, +e.g. \fIhasSubordinates\fP, \fIentryDN\fP and other implementation +dependent attributes are \fBNOT\fP generated at this point, for +consistency with the rest of slapd. This may change in the future. +.RE + +.TP +.B check_schema { YES | no } +Instructs the database to check schema adherence of entries after +modifications, and structural objectClass chain when entries are built. +By default it is set to +.BR yes . + +.TP +.B sqllayer <name> [...] +Loads the layer \fB<name>\fP onto a stack of helpers that are used +to map DNs from LDAP to SQL representation and vice-versa. +Subsequent args are passed to the layer configuration routine. +This is \fIhighly experimental\fP and should be used with extreme care. +The API of the layers is not frozen yet, so it is unpublished. + +.TP +.B autocommit { NO | yes } +Activates autocommit; by default, it is off. + +.SH METAINFORMATION USED +.LP +Almost everything mentioned later is illustrated in examples located +in the +.B servers/slapd/back\-sql/rdbms_depend/ +directory in the OpenLDAP source tree, and contains scripts for +generating sample database for Oracle, MS SQL Server, mySQL and more +(including PostgreSQL and IBM db2). +.LP +The first thing that one must arrange is what set of LDAP +object classes can present your RDBMS information. +.LP +The easiest way is to create an objectClass for each entity you had in +ER-diagram when designing your relational schema. +Any relational schema, no matter how normalized it is, was designed +after some model of your application's domain (for instance, accounts, +services etc. in ISP), and is used in terms of its entities, not just +tables of normalized schema. +It means that for every attribute of every such instance there is an +effective SQL query that loads its values. +.LP +Also you might want your object classes to conform to some of the standard +schemas like inetOrgPerson etc. +.LP +Nevertheless, when you think it out, we must define a way to translate +LDAP operation requests to (a series of) SQL queries. +Let us deal with the SEARCH operation. +.LP +Example: +Let's suppose that we store information about persons working in our +organization in two tables: +.LP +.nf + PERSONS PHONES + ---------- ------------- + id integer id integer + first_name varchar pers_id integer references persons(id) + last_name varchar phone + middle_name varchar + ... +.fi +.LP +(PHONES contains telephone numbers associated with persons). +A person can have several numbers, then PHONES contains several +records with corresponding pers_id, or no numbers (and no records in +PHONES with such pers_id). +An LDAP objectclass to present such information could look like this: +.LP +.nf + person + ------- + MUST cn + MAY telephoneNumber $ firstName $ lastName + ... +.fi +.LP +To fetch all values for cn attribute given person ID, we construct the +query: +.LP +.nf + SELECT CONCAT(persons.first_name,' ',persons.last_name) + AS cn FROM persons WHERE persons.id=? +.fi +.LP +for telephoneNumber we can use: +.LP +.nf + SELECT phones.phone AS telephoneNumber FROM persons,phones + WHERE persons.id=phones.pers_id AND persons.id=? +.fi +.LP +If we wanted to service LDAP requests with filters like +(telephoneNumber=123*), we would construct something like: +.LP +.nf + SELECT ... FROM persons,phones + WHERE persons.id=phones.pers_id + AND persons.id=? + AND phones.phone like '%1%2%3%' +.fi +.LP +(note how the telephoneNumber match is expanded in multiple wildcards +to account for interspersed ininfluential chars like spaces, dashes +and so; this occurs by design because telephoneNumber is defined after +a specially recognized syntax). +So, if we had information about what tables contain values for each +attribute, how to join these tables and arrange these values, we could +try to automatically generate such statements, and translate search +filters to SQL WHERE clauses. +.LP +To store such information, we add three more tables to our schema +and fill it with data (see samples): +.LP +.nf + ldap_oc_mappings (some columns are not listed for clarity) + --------------- + id=1 + name="person" + keytbl="persons" + keycol="id" +.fi +.LP +This table defines a mapping between objectclass (its name held in the +"name" column), and a table that holds the primary key for corresponding +entities. +For instance, in our example, the person entity, which we are trying +to present as "person" objectclass, resides in two tables (persons and +phones), and is identified by the persons.id column (that we will call +the primary key for this entity). +Keytbl and keycol thus contain "persons" (name of the table), and "id" +(name of the column). +.LP +.nf + ldap_attr_mappings (some columns are not listed for clarity) + ----------- + id=1 + oc_map_id=1 + name="cn" + sel_expr="CONCAT(persons.first_name,' ',persons.last_name)" + from_tbls="persons" + join_where=NULL + ************ + id=<n> + oc_map_id=1 + name="telephoneNumber" + sel_expr="phones.phone" + from_tbls="persons,phones" + join_where="phones.pers_id=persons.id" +.fi +.LP +This table defines mappings between LDAP attributes and SQL queries +that load their values. +Note that, unlike LDAP schema, these are not +.B attribute types +- the attribute "cn" for "person" objectclass can +have its values in different tables than "cn" for some other objectclass, +so attribute mappings depend on objectclass mappings (unlike attribute +types in LDAP schema, which are indifferent to objectclasses). +Thus, we have oc_map_id column with link to oc_mappings table. +.LP +Now we cut the SQL query that loads values for a given attribute into 3 parts. +First goes into sel_expr column - this is the expression we had +between SELECT and FROM keywords, which defines WHAT to load. +Next is table list - text between FROM and WHERE keywords. +It may contain aliases for convenience (see examples). +The last is part of the where clause, which (if it exists at all) expresses the +condition for joining the table containing values with the table +containing the primary key (foreign key equality and such). +If values are in the same table as the primary key, then this column is +left NULL (as for cn attribute above). +.LP +Having this information in parts, we are able to not only construct +queries that load attribute values by id of entry (for this we could +store SQL query as a whole), but to construct queries that load id's +of objects that correspond to a given search filter (or at least part of +it). +See below for examples. +.LP +.nf + ldap_entries + ------------ + id=1 + dn=<dn you choose> + oc_map_id=... + parent=<parent record id> + keyval=<value of primary key> +.fi +.LP +This table defines mappings between DNs of entries in your LDAP tree, +and values of primary keys for corresponding relational data. +It has recursive structure (parent column references id column of the +same table), which allows you to add any tree structure(s) to your +flat relational data. +Having id of objectclass mapping, we can determine table and column +for primary key, and keyval stores value of it, thus defining the exact +tuple corresponding to the LDAP entry with this DN. +.LP +Note that such design (see exact SQL table creation query) implies one +important constraint - the key must be an integer. +But all that I know about well-designed schemas makes me think that it's +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 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 +like this (by Robin Elfrink): +.LP +.nf + CREATE VIEW ldap_entries (id, dn, oc_map_id, parent, keyval) + AS + SELECT 0, UPPER('o=MyCompany,c=NL'), + 3, 0, 'baseObject' FROM unixusers WHERE userid='root' + UNION + SELECT (1000000000+userid), + UPPER(CONCAT(CONCAT('cn=',gecos),',o=MyCompany,c=NL')), + 1, 0, userid FROM unixusers + UNION + SELECT (2000000000+groupnummer), + UPPER(CONCAT(CONCAT('cn=',groupnaam),',o=MyCompany,c=NL')), + 2, 0, groupnummer FROM groups; +.fi + +.LP +If your RDBMS does not support +.B unions +in views, only one objectClass can be mapped in +.BR ldap_entries , +and the baseObject cannot be created; in this case, see the +.B baseObject +directive for a possible workaround. + +.LP +.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. +.LP +Example: +for our query with filter (telephoneNumber=123*) we would get the following +query generated (which loads candidate IDs) +.LP +.nf + SELECT ldap_entries.id,persons.id, 'person' AS objectClass, + ldap_entries.dn AS dn + FROM ldap_entries,persons,phones + WHERE persons.id=ldap_entries.keyval + AND ldap_entries.objclass=? + AND ldap_entries.parent=? + AND phones.pers_id=persons.id + AND (phones.phone LIKE '%1%2%3%') +.fi +.LP +(for ONELEVEL search) +or "... AND dn=?" (for BASE search) +or "... AND dn LIKE '%?'" (for SUBTREE) +.LP +Then, for each candidate, we load the requested attributes using +per-attribute queries like +.LP +.nf + SELECT phones.phone AS telephoneNumber + FROM persons,phones + WHERE persons.id=? AND phones.pers_id=persons.id +.fi +.LP +Then, we use test_filter() from the frontend API to test the entry for a full +LDAP search filter match (since we cannot effectively make sense of +SYNTAX of corresponding LDAP schema attribute, we translate the filter +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 +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 +- since as of this writing there are no stored procs in MySQL). +.LP +We just add more columns to ldap_oc_mappings and ldap_attr_mappings, holding +statements to execute (like create_proc, add_proc, del_proc etc.), and +flags governing the order of parameters passed to those statements. +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 +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 requires that one more table is added to the schema: +ldap_entry_objectclasses(entry_id,oc_name). +.LP +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 +for queries for "person" objectclass... +.LP +Referrals used to be implemented in a loose manner by adding an extra +table that allowed any entry to host a "ref" attribute, along with +a "referral" extra objectClass in table ldap_entry_objclasses. +In the current implementation, referrals are treated like any other +user-defined schema, since "referral" is a structural objectclass. +The suggested practice is to define a "referral" entry in ldap_oc_mappings, +holding a naming attribute, e.g. "ou" or "cn", a "ref" attribute, +containing the url; in case multiple referrals per entry are needed, +a separate table for urls can be created, where urls are mapped +to the respective entries. +The use of the naming attribute usually requires to add +an "extensibleObject" value to ldap_entry_objclasses. + +.LP +.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. +.LP +The \fBhasSubordintes\fP operational attribute is honored by back-sql +in search results and in compare operations; it is partially honored +also in filtering. Owing to design limitations, a (brain-dead?) filter +of the form +\fB(!(hasSubordinates=TRUE))\fP +will give no results instead of returning all the leaf entries, because +it actually expands into \fB... AND NOT (1=1)\fP. +If you need to find all the leaf entries, please use +\fB(hasSubordinates=FALSE)\fP +instead. +.LP +A directoryString value of the form "__First___Last_" +(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 through 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 +allows caching of LDAP search requests (queries) in a local database. +See +.BR slapo\-pcache (5) +for details. +.SH EXAMPLES +There are example SQL modules in the slapd/back\-sql/rdbms_depend/ +directory in the OpenLDAP source tree. +.SH ACCESS CONTROL +The +.B sql +backend honors access control semantics as indicated in +.BR slapd.access (5) +(including the +.B disclose +access privilege when enabled at compile time). +.SH FILES + +.TP +ETCDIR/slapd.conf +default slapd configuration file +.SH SEE ALSO +.BR slapd.conf (5), +.BR slapd (8). |