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Per the recent discussion there's been some code changes in JDBC's

Browse Source 
DatabaseMetaData.getColumn(). I proposed a patch that would change the
number of queries to find out all columns in a table from 2 * N + 1 to 1 (N
being the number of columns reported) by using some outer joins. I also
fixed the fact that getColumns() only returned columns that had a default
defined. OTOH, I did not use to change the code required for obtaining a
column's remarks (by using col_description() for 7.2  and requested by Tom
Lane).

Finally, I have found a way to get all the column details in a single query
*and* use col_description() for 7.2 servers. A patch is attached. It
overrules Ren? Pijlman's fix for this that was committed just today, but
still used N + 1 queries (sorry Ren? ;-) )

I also fixed the return values for TABLE_CAT and TABLE_SCHEM from "" to
null, to be more standard compliant (and requested in Ren?'s mail found at
http://fts.postgresql.org/db/mw/msg.html?mid=1034253).

As always, the JDBC1 version has not been tested as I have no JDK 1.1

Jeroen van Vianen
REL7_2_STABLE
Bruce Momjian 25 years ago
parent 5b328502b5
commit 07ce9fe61d
2 changed files with 216 additions and 196 deletions
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  1. 132
      src/interfaces/jdbc/org/postgresql/jdbc1/DatabaseMetaData.java
  2. 132
      src/interfaces/jdbc/org/postgresql/jdbc2/DatabaseMetaData.java

132
src/interfaces/jdbc/org/postgresql/jdbc1/DatabaseMetaData.java
Unescape View File

@ -13,7 +13,7 @@ import org.postgresql.util.PSQLException;
/**
* This class provides information about the database as a whole.
*
* $Id: DatabaseMetaData.java,v 1.32 2001/09/10 14:55:08 momjian Exp $
* $Id: DatabaseMetaData.java,v 1.33 2001/09/29 03:08:01 momjian Exp $
*
* <p>Many of the methods here return lists of information in ResultSets. You
* can use the normal ResultSet methods such as getString and getInt to
@ -1895,10 +1895,8 @@ public class DatabaseMetaData implements java.sql.DatabaseMetaData
*/
public java.sql.ResultSet getColumns(String catalog, String schemaPattern, String tableNamePattern, String columnNamePattern) throws SQLException
{
// the field descriptors for the new ResultSet
Field f[] = new Field[18];
java.sql.ResultSet r; // ResultSet for the SQL query that we need to do
Vector v = new Vector(); // The new ResultSet tuple stuff
Field f[] = new Field[18]; // The field descriptors for the new ResultSet
f[0] = new Field(connection, "TABLE_CAT", iVarcharOid, 32);
f[1] = new Field(connection, "TABLE_SCHEM", iVarcharOid, 32);
@ -1919,56 +1917,73 @@ public class DatabaseMetaData implements java.sql.DatabaseMetaData
f[16] = new Field(connection, "ORDINAL_POSITION", iInt4Oid,4);
f[17] = new Field(connection, "IS_NULLABLE", iVarcharOid, 32);
// Added by Stefan Andreasen <stefan@linux.kapow.dk>
// If the pattern are null then set them to %
if (tableNamePattern == null) tableNamePattern="%";
if (columnNamePattern == null) columnNamePattern="%";
// Now form the query
String query =
"select " +
(connection.haveMinimumServerVersion("7.2") ? "a.attrelid" : "a.oid") +
",c.relname,a.attname,a.atttypid," +
"a.attnum,a.attnotnull,a.attlen,a.atttypmod,d.adsrc " +
"from (pg_class c inner join pg_attribute a " +
"on (c.oid=a.attrelid) ) " +
"left outer join pg_attrdef d " +
"on (c.oid=d.adrelid and d.adnum=a.attnum) " +
"where " +
"c.relname like '"+tableNamePattern.toLowerCase()+"' and " +
"a.attname like '"+columnNamePattern.toLowerCase()+"' and " +
"a.attnum>0 " +
"order by c.relname,a.attnum";
r = connection.ExecSQL(query);
StringBuffer sql = new StringBuffer(512);
/* Build a >= 7.1 SQL statement to list all columns */
sql.append("select " +
(connection.haveMinimumServerVersion("7.2") ? "a.attrelid, " : "a.oid, ") +
" c.relname, " +
" a.attname, " +
" a.atttypid, " +
" a.attnum, " +
" a.attnotnull, " +
" a.attlen, " +
" a.atttypmod, " +
" d.adsrc, " +
" t.typname, " +
/* Use the new col_description in 7.2 or an additional outer join in 7.1 */
(connection.haveMinimumServerVersion("7.2") ? "col_description(a.attrelid, a.attnum) " : "e.description ") +
"from" +
" (" +
" (pg_class c inner join pg_attribute a on" +
" (" +
" a.attrelid=c.oid");
if ((tableNamePattern != null) && ! tableNamePattern.equals("%")) {
sql.append(" and c.relname like \'" + tableNamePattern + "\'");
}
if ((columnNamePattern != null) && ! columnNamePattern.equals("%")) {
sql.append(" and a.attname like \'" + columnNamePattern + "\'");
}
sql.append(
" and a.attnum > 0" +
" )" +
" ) inner join pg_type t on" +
" (" +
" t.oid = a.atttypid" +
" )" +
" )" +
" left outer join pg_attrdef d on" +
" (" +
" c.oid = d.adrelid" +
" and a.attnum = d.adnum" +
" ) ");
if (!connection.haveMinimumServerVersion("7.2")) {
/* Only for 7.1 */
sql.append(
" left outer join pg_description e on" +
" (" +
" e.objoid = a.oid" +
" ) ");
}
sql.append("order by" +
" c.relname, a.attnum");
java.sql.ResultSet r = connection.ExecSQL(sql.toString());
while (r.next()) {
byte[][] tuple = new byte[18][0];
// Fetch the description for the table (if any)
String getDescriptionStatement =
connection.haveMinimumServerVersion("7.2") ?
"select col_description(" + r.getInt(1) + "," + r.getInt(5) + ")" :
"select description from pg_description where objoid=" + r.getInt(1);
java.sql.ResultSet dr = connection.ExecSQL(getDescriptionStatement);
if(((org.postgresql.ResultSet)dr).getTupleCount()==1) {
dr.next();
tuple[11] = dr.getBytes(1);
} else
tuple[11] = null;
dr.close();
String nullFlag = r.getString(6);
String typname = r.getString(10);
tuple[0] = "".getBytes(); // Catalog name
tuple[1] = "".getBytes(); // Schema name
tuple[0] = null; // Catalog name, not supported
tuple[1] = null; // Schema name, not supported
tuple[2] = r.getBytes(2); // Table name
tuple[3] = r.getBytes(3); // Column name
dr = connection.ExecSQL("select typname from pg_type where oid = "+r.getString(4));
dr.next();
String typname=dr.getString(1);
dr.close();
tuple[4] = Integer.toString(connection.getSQLType(typname)).getBytes(); // Data type
tuple[5] = typname.getBytes(); // Type name
@ -1979,33 +1994,28 @@ public class DatabaseMetaData implements java.sql.DatabaseMetaData
if (typname.equals("bpchar") || typname.equals("varchar")) {
int atttypmod = r.getInt(8);
tuple[6] = Integer.toString(atttypmod != -1 ? atttypmod - VARHDRSZ : 0).getBytes();
} else
} else {
tuple[6] = r.getBytes(7);
}
tuple[7] = null; // Buffer length
tuple[8] = "0".getBytes(); // Decimal Digits - how to get this?
tuple[9] = "10".getBytes(); // Num Prec Radix - assume decimal
// tuple[10] is below
// tuple[11] is above
tuple[12] = r.getBytes(9); // column default
tuple[10] = Integer.toString(nullFlag.equals("f") ?
java.sql.DatabaseMetaData.columnNullable :
java.sql.DatabaseMetaData.columnNoNulls).getBytes(); // Nullable
tuple[11] = r.getBytes(11); // Description (if any)
tuple[12] = r.getBytes(9); // Column default
tuple[13] = null; // sql data type (unused)
tuple[14] = null; // sql datetime sub (unused)
tuple[15] = tuple[6]; // char octet length
tuple[16] = r.getBytes(5); // ordinal position
String nullFlag = r.getString(6);
tuple[10] = Integer.toString(nullFlag.equals("f")?java.sql.DatabaseMetaData.columnNullable:java.sql.DatabaseMetaData.columnNoNulls).getBytes(); // Nullable
tuple[17] = (nullFlag.equals("f")?"YES":"NO").getBytes(); // is nullable
tuple[17] = (nullFlag.equals("f") ? "YES" : "NO").getBytes(); // Is nullable
v.addElement(tuple);
}
r.close();
return new ResultSet(connection, f, v, "OK", 1);
}

132
src/interfaces/jdbc/org/postgresql/jdbc2/DatabaseMetaData.java
Unescape View File

@ -13,7 +13,7 @@ import org.postgresql.util.PSQLException;
/**
* This class provides information about the database as a whole.
*
* $Id: DatabaseMetaData.java,v 1.36 2001/09/10 14:55:08 momjian Exp $
* $Id: DatabaseMetaData.java,v 1.37 2001/09/29 03:08:01 momjian Exp $
*
* <p>Many of the methods here return lists of information in ResultSets. You
* can use the normal ResultSet methods such as getString and getInt to
@ -1895,10 +1895,8 @@ public class DatabaseMetaData implements java.sql.DatabaseMetaData
*/
public java.sql.ResultSet getColumns(String catalog, String schemaPattern, String tableNamePattern, String columnNamePattern) throws SQLException
{
// the field descriptors for the new ResultSet
Field f[] = new Field[18];
java.sql.ResultSet r; // ResultSet for the SQL query that we need to do
Vector v = new Vector(); // The new ResultSet tuple stuff
Field f[] = new Field[18]; // The field descriptors for the new ResultSet
f[0] = new Field(connection, "TABLE_CAT", iVarcharOid, 32);
f[1] = new Field(connection, "TABLE_SCHEM", iVarcharOid, 32);
@ -1919,56 +1917,73 @@ public class DatabaseMetaData implements java.sql.DatabaseMetaData
f[16] = new Field(connection, "ORDINAL_POSITION", iInt4Oid,4);
f[17] = new Field(connection, "IS_NULLABLE", iVarcharOid, 32);
// Added by Stefan Andreasen <stefan@linux.kapow.dk>
// If the pattern are null then set them to %
if (tableNamePattern == null) tableNamePattern="%";
if (columnNamePattern == null) columnNamePattern="%";
// Now form the query
String query =
"select " +
(connection.haveMinimumServerVersion("7.2") ? "a.attrelid" : "a.oid") +
",c.relname,a.attname,a.atttypid," +
"a.attnum,a.attnotnull,a.attlen,a.atttypmod,d.adsrc " +
"from (pg_class c inner join pg_attribute a " +
"on (c.oid=a.attrelid) ) " +
"left outer join pg_attrdef d " +
"on (c.oid=d.adrelid and d.adnum=a.attnum) " +
"where " +
"c.relname like '"+tableNamePattern.toLowerCase()+"' and " +
"a.attname like '"+columnNamePattern.toLowerCase()+"' and " +
"a.attnum>0 " +
"order by c.relname,a.attnum";
r = connection.ExecSQL(query);
StringBuffer sql = new StringBuffer(512);
/* Build a >= 7.1 SQL statement to list all columns */
sql.append("select " +
(connection.haveMinimumServerVersion("7.2") ? "a.attrelid, " : "a.oid, ") +
" c.relname, " +
" a.attname, " +
" a.atttypid, " +
" a.attnum, " +
" a.attnotnull, " +
" a.attlen, " +
" a.atttypmod, " +
" d.adsrc, " +
" t.typname, " +
/* Use the new col_description in 7.2 or an additional outer join in 7.1 */
(connection.haveMinimumServerVersion("7.2") ? "col_description(a.attrelid, a.attnum) " : "e.description ") +
"from" +
" (" +
" (pg_class c inner join pg_attribute a on" +
" (" +
" a.attrelid=c.oid");
if ((tableNamePattern != null) && ! tableNamePattern.equals("%")) {
sql.append(" and c.relname like \'" + tableNamePattern + "\'");
}
if ((columnNamePattern != null) && ! columnNamePattern.equals("%")) {
sql.append(" and a.attname like \'" + columnNamePattern + "\'");
}
sql.append(
" and a.attnum > 0" +
" )" +
" ) inner join pg_type t on" +
" (" +
" t.oid = a.atttypid" +
" )" +
" )" +
" left outer join pg_attrdef d on" +
" (" +
" c.oid = d.adrelid" +
" and a.attnum = d.adnum" +
" ) ");
if (!connection.haveMinimumServerVersion("7.2")) {
/* Only for 7.1 */
sql.append(
" left outer join pg_description e on" +
" (" +
" e.objoid = a.oid" +
" ) ");
}
sql.append("order by" +
" c.relname, a.attnum");
java.sql.ResultSet r = connection.ExecSQL(sql.toString());
while (r.next()) {
byte[][] tuple = new byte[18][0];
// Fetch the description for the table (if any)
String getDescriptionStatement =
connection.haveMinimumServerVersion("7.2") ?
"select col_description(" + r.getInt(1) + "," + r.getInt(5) + ")" :
"select description from pg_description where objoid=" + r.getInt(1);
java.sql.ResultSet dr = connection.ExecSQL(getDescriptionStatement);
if(((org.postgresql.ResultSet)dr).getTupleCount()==1) {
dr.next();
tuple[11] = dr.getBytes(1);
} else
tuple[11] = null;
dr.close();
String nullFlag = r.getString(6);
String typname = r.getString(10);
tuple[0] = "".getBytes(); // Catalog name
tuple[1] = "".getBytes(); // Schema name
tuple[0] = null; // Catalog name, not supported
tuple[1] = null; // Schema name, not supported
tuple[2] = r.getBytes(2); // Table name
tuple[3] = r.getBytes(3); // Column name
dr = connection.ExecSQL("select typname from pg_type where oid = "+r.getString(4));
dr.next();
String typname=dr.getString(1);
dr.close();
tuple[4] = Integer.toString(connection.getSQLType(typname)).getBytes(); // Data type
tuple[5] = typname.getBytes(); // Type name
@ -1979,33 +1994,28 @@ public class DatabaseMetaData implements java.sql.DatabaseMetaData
if (typname.equals("bpchar") || typname.equals("varchar")) {
int atttypmod = r.getInt(8);
tuple[6] = Integer.toString(atttypmod != -1 ? atttypmod - VARHDRSZ : 0).getBytes();
} else
} else {
tuple[6] = r.getBytes(7);
}
tuple[7] = null; // Buffer length
tuple[8] = "0".getBytes(); // Decimal Digits - how to get this?
tuple[9] = "10".getBytes(); // Num Prec Radix - assume decimal
// tuple[10] is below
// tuple[11] is above
tuple[12] = r.getBytes(9); // column default
tuple[10] = Integer.toString(nullFlag.equals("f") ?
java.sql.DatabaseMetaData.columnNullable :
java.sql.DatabaseMetaData.columnNoNulls).getBytes(); // Nullable
tuple[11] = r.getBytes(11); // Description (if any)
tuple[12] = r.getBytes(9); // Column default
tuple[13] = null; // sql data type (unused)
tuple[14] = null; // sql datetime sub (unused)
tuple[15] = tuple[6]; // char octet length
tuple[16] = r.getBytes(5); // ordinal position
String nullFlag = r.getString(6);
tuple[10] = Integer.toString(nullFlag.equals("f")?java.sql.DatabaseMetaData.columnNullable:java.sql.DatabaseMetaData.columnNoNulls).getBytes(); // Nullable
tuple[17] = (nullFlag.equals("f")?"YES":"NO").getBytes(); // is nullable
tuple[17] = (nullFlag.equals("f") ? "YES" : "NO").getBytes(); // Is nullable
v.addElement(tuple);
}
r.close();
return new ResultSet(connection, f, v, "OK", 1);
}

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