Skip to content

Commit 07ce9fe

Browse files
bmomjianbmomjian
committed
Per the recent discussion there's been some code changes in JDBC's
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
1 parent 5b32850 commit 07ce9fe

File tree

2 files changed

+216
-196
lines changed

2 files changed

+216
-196
lines changed

‎src/interfaces/jdbc/org/postgresql/jdbc1/DatabaseMetaData.java

Lines changed: 108 additions & 98 deletions
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@
1313
/**
1414
* This class provides information about the database as a whole.
1515
*
16-
* $Id: DatabaseMetaData.java,v 1.32 2001/09/10 14:55:08 momjian Exp $
16+
* $Id: DatabaseMetaData.java,v 1.33 2001/09/29 03:08:01 momjian Exp $
1717
*
1818
* <p>Many of the methods here return lists of information in ResultSets. You
1919
* can use the normal ResultSet methods such as getString and getInt to
@@ -1895,21 +1895,19 @@ public java.sql.ResultSet getTableTypes() throws SQLException
18951895
*/
18961896
public java.sql.ResultSet getColumns(String catalog, String schemaPattern, String tableNamePattern, String columnNamePattern) throws SQLException
18971897
{
1898-
// the field descriptors for the new ResultSet
1899-
Field f[] = new Field[18];
1900-
java.sql.ResultSet r; // ResultSet for the SQL query that we need to do
19011898
Vector v = new Vector(); // The new ResultSet tuple stuff
1902-
1903-
f[0] = new Field(connection, "TABLE_CAT", iVarcharOid, 32);
1904-
f[1] = new Field(connection, "TABLE_SCHEM", iVarcharOid, 32);
1905-
f[2] = new Field(connection, "TABLE_NAME", iVarcharOid, 32);
1906-
f[3] = new Field(connection, "COLUMN_NAME", iVarcharOid, 32);
1907-
f[4] = new Field(connection, "DATA_TYPE", iInt2Oid, 2);
1908-
f[5] = new Field(connection, "TYPE_NAME", iVarcharOid, 32);
1909-
f[6] = new Field(connection, "COLUMN_SIZE", iInt4Oid, 4);
1910-
f[7] = new Field(connection, "BUFFER_LENGTH", iVarcharOid, 32);
1911-
f[8] = new Field(connection, "DECIMAL_DIGITS", iInt4Oid, 4);
1912-
f[9] = new Field(connection, "NUM_PREC_RADIX", iInt4Oid, 4);
1899+
Field f[] = new Field[18]; // The field descriptors for the new ResultSet
1900+
1901+
f[0] = new Field(connection, "TABLE_CAT", iVarcharOid, 32);
1902+
f[1] = new Field(connection, "TABLE_SCHEM", iVarcharOid, 32);
1903+
f[2] = new Field(connection, "TABLE_NAME", iVarcharOid, 32);
1904+
f[3] = new Field(connection, "COLUMN_NAME", iVarcharOid, 32);
1905+
f[4] = new Field(connection, "DATA_TYPE", iInt2Oid, 2);
1906+
f[5] = new Field(connection, "TYPE_NAME", iVarcharOid, 32);
1907+
f[6] = new Field(connection, "COLUMN_SIZE", iInt4Oid, 4);
1908+
f[7] = new Field(connection, "BUFFER_LENGTH", iVarcharOid, 32);
1909+
f[8] = new Field(connection, "DECIMAL_DIGITS", iInt4Oid, 4);
1910+
f[9] = new Field(connection, "NUM_PREC_RADIX", iInt4Oid, 4);
19131911
f[10] = new Field(connection, "NULLABLE", iInt4Oid, 4);
19141912
f[11] = new Field(connection, "REMARKS", iVarcharOid, 32);
19151913
f[12] = new Field(connection, "COLUMN_DEF", iVarcharOid, 32);
@@ -1919,93 +1917,105 @@ public java.sql.ResultSet getColumns(String catalog, String schemaPattern, Strin
19191917
f[16] = new Field(connection, "ORDINAL_POSITION", iInt4Oid,4);
19201918
f[17] = new Field(connection, "IS_NULLABLE", iVarcharOid, 32);
19211919

1922-
// Added by Stefan Andreasen <stefan@linux.kapow.dk>
1923-
// If the pattern are null then set them to %
1924-
if (tableNamePattern == null) tableNamePattern="%";
1925-
if (columnNamePattern == null) columnNamePattern="%";
1926-
1927-
// Now form the query
1928-
String query =
1929-
"select " +
1930-
(connection.haveMinimumServerVersion("7.2") ? "a.attrelid" : "a.oid") +
1931-
",c.relname,a.attname,a.atttypid," +
1932-
"a.attnum,a.attnotnull,a.attlen,a.atttypmod,d.adsrc " +
1933-
"from (pg_class c inner join pg_attribute a " +
1934-
"on (c.oid=a.attrelid) ) " +
1935-
"left outer join pg_attrdef d " +
1936-
"on (c.oid=d.adrelid and d.adnum=a.attnum) " +
1937-
"where " +
1938-
"c.relname like '"+tableNamePattern.toLowerCase()+"' and " +
1939-
"a.attname like '"+columnNamePattern.toLowerCase()+"' and " +
1940-
"a.attnum>0 " +
1941-
"order by c.relname,a.attnum";
1942-
1943-
r = connection.ExecSQL(query);
1944-
1945-
while(r.next()) {
1946-
byte[][] tuple = new byte[18][0];
1947-
1948-
// Fetch the description for the table (if any)
1949-
String getDescriptionStatement =
1950-
connection.haveMinimumServerVersion("7.2") ?
1951-
"select col_description(" + r.getInt(1) + "," + r.getInt(5) + ")" :
1952-
"select description from pg_description where objoid=" + r.getInt(1);
1953-
1954-
java.sql.ResultSet dr = connection.ExecSQL(getDescriptionStatement);
1955-
1956-
if(((org.postgresql.ResultSet)dr).getTupleCount()==1) {
1957-
dr.next();
1958-
tuple[11] = dr.getBytes(1);
1959-
} else
1960-
tuple[11] = null;
1961-
dr.close();
1962-
1963-
tuple[0] = "".getBytes(); // Catalog name
1964-
tuple[1] = "".getBytes(); // Schema name
1965-
tuple[2] = r.getBytes(2); // Table name
1966-
tuple[3] = r.getBytes(3); // Column name
1967-
1968-
dr = connection.ExecSQL("select typname from pg_type where oid = "+r.getString(4));
1969-
dr.next();
1970-
String typname=dr.getString(1);
1971-
dr.close();
1972-
tuple[4] = Integer.toString(connection.getSQLType(typname)).getBytes(); // Data type
1973-
tuple[5] = typname.getBytes(); // Type name
1974-
1975-
// Column size
1976-
// Looking at the psql source,
1977-
// I think the length of a varchar as specified when the table was created
1978-
// should be extracted from atttypmod which contains this length + sizeof(int32)
1979-
if (typname.equals("bpchar") || typname.equals("varchar")) {
1980-
int atttypmod = r.getInt(8);
1981-
tuple[6] = Integer.toString(atttypmod != -1 ? atttypmod - VARHDRSZ : 0).getBytes();
1982-
} else
1983-
tuple[6] = r.getBytes(7);
1984-
1985-
tuple[7] = null; // Buffer length
1986-
1987-
tuple[8] = "0".getBytes(); // Decimal Digits - how to get this?
1988-
tuple[9] = "10".getBytes(); // Num Prec Radix - assume decimal
1989-
1990-
// tuple[10] is below
1991-
// tuple[11] is above
1992-
1993-
tuple[12] = r.getBytes(9); // column default
1994-
1995-
tuple[13] = null; // sql data type (unused)
1996-
tuple[14] = null; // sql datetime sub (unused)
1920+
StringBuffer sql = new StringBuffer(512);
1921+
1922+
/* Build a >= 7.1 SQL statement to list all columns */
1923+
sql.append("select " +
1924+
(connection.haveMinimumServerVersion("7.2") ? "a.attrelid, " : "a.oid, ") +
1925+
" c.relname, " +
1926+
" a.attname, " +
1927+
" a.atttypid, " +
1928+
" a.attnum, " +
1929+
" a.attnotnull, " +
1930+
" a.attlen, " +
1931+
" a.atttypmod, " +
1932+
" d.adsrc, " +
1933+
" t.typname, " +
1934+
/* Use the new col_description in 7.2 or an additional outer join in 7.1 */
1935+
(connection.haveMinimumServerVersion("7.2") ? "col_description(a.attrelid, a.attnum) " : "e.description ") +
1936+
"from" +
1937+
" (" +
1938+
" (pg_class c inner join pg_attribute a on" +
1939+
" (" +
1940+
" a.attrelid=c.oid");
1941+
1942+
if ((tableNamePattern != null) && ! tableNamePattern.equals("%")) {
1943+
sql.append(" and c.relname like \'" + tableNamePattern + "\'");
1944+
}
19971945

1998-
tuple[15] = tuple[6]; // char octet length
1946+
if ((columnNamePattern != null) && ! columnNamePattern.equals("%")) {
1947+
sql.append(" and a.attname like \'" + columnNamePattern + "\'");
1948+
}
19991949

2000-
tuple[16] = r.getBytes(5); // ordinal position
1950+
sql.append(
1951+
" and a.attnum > 0" +
1952+
" )" +
1953+
" ) inner join pg_type t on" +
1954+
" (" +
1955+
" t.oid = a.atttypid" +
1956+
" )" +
1957+
" )" +
1958+
" left outer join pg_attrdef d on" +
1959+
" (" +
1960+
" c.oid = d.adrelid" +
1961+
" and a.attnum = d.adnum" +
1962+
" ) ");
1963+
1964+
if (!connection.haveMinimumServerVersion("7.2")) {
1965+
/* Only for 7.1 */
1966+
sql.append(
1967+
" left outer join pg_description e on" +
1968+
" (" +
1969+
" e.objoid = a.oid" +
1970+
" ) ");
1971+
}
20011972

2002-
String nullFlag = r.getString(6);
2003-
tuple[10] = Integer.toString(nullFlag.equals("f")?java.sql.DatabaseMetaData.columnNullable:java.sql.DatabaseMetaData.columnNoNulls).getBytes(); // Nullable
2004-
tuple[17] = (nullFlag.equals("f")?"YES":"NO").getBytes(); // is nullable
1973+
sql.append("order by" +
1974+
" c.relname, a.attnum");
1975+
1976+
java.sql.ResultSet r = connection.ExecSQL(sql.toString());
1977+
while (r.next()) {
1978+
byte[][] tuple = new byte[18][0];
1979+
1980+
String nullFlag = r.getString(6);
1981+
String typname = r.getString(10);
1982+
1983+
tuple[0] = null; // Catalog name, not supported
1984+
tuple[1] = null; // Schema name, not supported
1985+
tuple[2] = r.getBytes(2); // Table name
1986+
tuple[3] = r.getBytes(3); // Column name
1987+
tuple[4] = Integer.toString(connection.getSQLType(typname)).getBytes(); // Data type
1988+
tuple[5] = typname.getBytes(); // Type name
1989+
1990+
// Column size
1991+
// Looking at the psql source,
1992+
// I think the length of a varchar as specified when the table was created
1993+
// should be extracted from atttypmod which contains this length + sizeof(int32)
1994+
if (typname.equals("bpchar") || typname.equals("varchar")) {
1995+
int atttypmod = r.getInt(8);
1996+
tuple[6] = Integer.toString(atttypmod != -1 ? atttypmod - VARHDRSZ : 0).getBytes();
1997+
} else {
1998+
tuple[6] = r.getBytes(7);
1999+
}
2000+
2001+
tuple[7] = null; // Buffer length
2002+
tuple[8] = "0".getBytes(); // Decimal Digits - how to get this?
2003+
tuple[9] = "10".getBytes(); // Num Prec Radix - assume decimal
2004+
tuple[10] = Integer.toString(nullFlag.equals("f") ?
2005+
java.sql.DatabaseMetaData.columnNullable :
2006+
java.sql.DatabaseMetaData.columnNoNulls).getBytes(); // Nullable
2007+
tuple[11] = r.getBytes(11); // Description (if any)
2008+
tuple[12] = r.getBytes(9); // Column default
2009+
tuple[13] = null; // sql data type (unused)
2010+
tuple[14] = null; // sql datetime sub (unused)
2011+
tuple[15] = tuple[6]; // char octet length
2012+
tuple[16] = r.getBytes(5); // ordinal position
2013+
tuple[17] = (nullFlag.equals("f") ? "YES" : "NO").getBytes(); // Is nullable
2014+
2015+
v.addElement(tuple);
2016+
}
2017+
r.close();
20052018

2006-
v.addElement(tuple);
2007-
}
2008-
r.close();
20092019
return new ResultSet(connection, f, v, "OK", 1);
20102020
}
20112021

0 commit comments

Comments
 (0)
pFad - Phonifier reborn

Pfad - The Proxy pFad of © 2024 Garber Painting. All rights reserved.

Note: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.


Alternative Proxies:

Alternative Proxy

pFad Proxy

pFad v3 Proxy

pFad v4 Proxy