<command>EXPLAIN</command>.
    </para>

   </sect2>

   <sect2 id="fdw-callbacks-analyze">
    <title>FDW Routines for <command>ANALYZE</command></title>

    <para>
<programlisting>
bool
AnalyzeForeignTable(Relation relation,
                    AcquireSampleRowsFunc *func,
                    BlockNumber *totalpages);
</programlisting>

     This function is called when <xref linkend="sql-analyze"/> is executed on
     a foreign table.  If the FDW can collect statistics for this
     foreign table, it should return <literal>true</literal>, and provide a pointer
     to a function that will collect sample rows from the table in
     <parameter>func</parameter>, plus the estimated size of the table in pages in
     <parameter>totalpages</parameter>.  Otherwise, return <literal>false</literal>.
    </para>

    <para>
     If the FDW does not support collecting statistics for any tables, the
     <function>AnalyzeForeignTable</function> pointer can be set to <literal>NULL</literal>.
    </para>

    <para>
     If provided, the sample collection function must have the signature
<programlisting>
int
AcquireSampleRowsFunc(Relation relation,
                      int elevel,
                      HeapTuple *rows,
                      int targrows,
                      double *totalrows,
                      double *totaldeadrows);
</programlisting>

     A random sample of up to <parameter>targrows</parameter> rows should be collected
     from the table and stored into the caller-provided <parameter>rows</parameter>
     array.  The actual number of rows collected must be returned.  In
     addition, store estimates of the total numbers of live and dead rows in
     the table into the output parameters <parameter>totalrows</parameter> and
     <parameter>totaldeadrows</parameter>.  (Set <parameter>totaldeadrows</parameter> to zero
     if the FDW does not have any concept of dead rows.)
    </para>

   </sect2>

   <sect2 id="fdw-callbacks-import">
    <title>FDW Routines for <command>IMPORT FOREIGN SCHEMA</command></title>

    <para>
<programlisting>
List *
ImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid);
</programlisting>

     Obtain a list of foreign table creation commands.  This function is
     called when executing <xref linkend="sql-importforeignschema"/>, and is
     passed the parse tree for that statement, as well as the OID of the
     foreign server to use.  It should return a list of C strings, each of
     which must contain a <xref linkend="sql-createforeigntable"/> command.
     These strings will be parsed and executed by the core server.
    </para>

    <para>
     Within the <structname>ImportForeignSchemaStmt</structname> struct,
     <structfield>remote_schema</structfield> is the name of the remote schema from
     which tables are to be imported.
     <structfield>list_type</structfield> identifies how to filter table names:
     <literal>FDW_IMPORT_SCHEMA_ALL</literal> means that all tables in the remote
     schema should be imported (in this case <structfield>table_list</structfield> is
     empty), <literal>FDW_IMPORT_SCHEMA_LIMIT_TO</literal> means to include only
     tables listed in <structfield>table_list</structfield>,
     and <literal>FDW_IMPORT_SCHEMA_EXCEPT</literal> means to exclude the tables
     listed in <structfield>table_list</structfield>.
     <structfield>options</structfield> is a list of options used for the import process.
     The meanings of the options are up to the FDW.
     For example, an FDW could use an option to define whether the
     <literal>NOT NULL</literal> attributes of columns should be imported.
     These options need not have anything to do with those supported by the
     FDW as database object options.
    </para>

    <para>
     The FDW may ignore the <structfield>local_schema</structfield> field of
     the <structname>ImportForeignSchemaStmt</structname>, because the core server
     will automatically insert that name into the