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Commit57040f7

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Attached is a patch for JDBC's getColumn() function that was broken /
flawed in the following ways:1. Only returned columns that had a default value defined, rather than allcolumns in a table2. Used 2 * N + 1 queries to find out attributes, comments and typenamesfor N columns.By using some outer join syntax it is possible to retrieve all necessaryinformation in just one SQL statement. This means this version is onlysuitable for PostgreSQL >= 7.1. Don't know whether that's a problem.I've tested this function with current sources and 7.1.3 and patched bothjdbc1 and jdbc2. I haven't compiled nor tested the jdbc1 version though, asI have no JDK 1.1 available.Note the discussion inhttp://fts.postgresql.org/db/mw/msg.html?mid=1029626regarding differences in obtaining comments on database object in 7.1 and7.2. I was unable to use the following syntax (or similar ones):select ..., descriptionfrom ... left outer join col_description(a.attrelid, a.attnum) descriptionorder by c.relname, a.attnum;(the error was parse error at or near '(') so I had to paste the actualcode for the col_description function into the left outer join. Maybesomeone who is more knowledgable about outer joins might provide me with abetter SQL statement.Jeroen van Vianen
1 parent0b71596 commit57040f7

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2 files changed

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-193
lines changed

2 files changed

+230
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‎src/interfaces/jdbc/org/postgresql/jdbc1/DatabaseMetaData.java

Lines changed: 112 additions & 93 deletions
Original file line numberDiff line numberDiff line change
@@ -13,6 +13,8 @@
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/**
1414
* This class provides information about the database as a whole.
1515
*
16+
* $Id: DatabaseMetaData.java,v 1.30 2001/09/06 03:20:30 momjian Exp $
17+
*
1618
* <p>Many of the methods here return lists of information in ResultSets. You
1719
* can use the normal ResultSet methods such as getString and getInt to
1820
* retrieve the data from these ResultSets. If a given form of metadata is
@@ -1893,21 +1895,19 @@ public java.sql.ResultSet getTableTypes() throws SQLException
18931895
*/
18941896
publicjava.sql.ResultSetgetColumns(Stringcatalog,StringschemaPattern,StringtableNamePattern,StringcolumnNamePattern)throwsSQLException
18951897
{
1896-
// the field descriptors for the new ResultSet
1897-
Fieldf[] =newField[18];
1898-
java.sql.ResultSetr;// ResultSet for the SQL query that we need to do
18991898
Vectorv =newVector();// The new ResultSet tuple stuff
1900-
1901-
f[0] =newField(connection,"TABLE_CAT",iVarcharOid,32);
1902-
f[1] =newField(connection,"TABLE_SCHEM",iVarcharOid,32);
1903-
f[2] =newField(connection,"TABLE_NAME",iVarcharOid,32);
1904-
f[3] =newField(connection,"COLUMN_NAME",iVarcharOid,32);
1905-
f[4] =newField(connection,"DATA_TYPE",iInt2Oid,2);
1906-
f[5] =newField(connection,"TYPE_NAME",iVarcharOid,32);
1907-
f[6] =newField(connection,"COLUMN_SIZE",iInt4Oid,4);
1908-
f[7] =newField(connection,"BUFFER_LENGTH",iVarcharOid,32);
1909-
f[8] =newField(connection,"DECIMAL_DIGITS",iInt4Oid,4);
1910-
f[9] =newField(connection,"NUM_PREC_RADIX",iInt4Oid,4);
1899+
Fieldf[] =newField[18];// The field descriptors for the new ResultSet
1900+
1901+
f[0] =newField(connection,"TABLE_CAT",iVarcharOid,32);
1902+
f[1] =newField(connection,"TABLE_SCHEM",iVarcharOid,32);
1903+
f[2] =newField(connection,"TABLE_NAME",iVarcharOid,32);
1904+
f[3] =newField(connection,"COLUMN_NAME",iVarcharOid,32);
1905+
f[4] =newField(connection,"DATA_TYPE",iInt2Oid,2);
1906+
f[5] =newField(connection,"TYPE_NAME",iVarcharOid,32);
1907+
f[6] =newField(connection,"COLUMN_SIZE",iInt4Oid,4);
1908+
f[7] =newField(connection,"BUFFER_LENGTH",iVarcharOid,32);
1909+
f[8] =newField(connection,"DECIMAL_DIGITS",iInt4Oid,4);
1910+
f[9] =newField(connection,"NUM_PREC_RADIX",iInt4Oid,4);
19111911
f[10] =newField(connection,"NULLABLE",iInt4Oid,4);
19121912
f[11] =newField(connection,"REMARKS",iVarcharOid,32);
19131913
f[12] =newField(connection,"COLUMN_DEF",iVarcharOid,32);
@@ -1917,91 +1917,110 @@ public java.sql.ResultSet getColumns(String catalog, String schemaPattern, Strin
19171917
f[16] =newField(connection,"ORDINAL_POSITION",iInt4Oid,4);
19181918
f[17] =newField(connection,"IS_NULLABLE",iVarcharOid,32);
19191919

1920-
// Added by Stefan Andreasen <stefan@linux.kapow.dk>
1921-
// If the pattern are null then set them to %
1922-
if (tableNamePattern ==null)tableNamePattern="%";
1923-
if (columnNamePattern ==null)columnNamePattern="%";
1924-
1925-
// Now form the query
1926-
Stringquery =
1927-
"select " +
1928-
(connection.haveMinimumServerVersion("7.2") ?"a.attrelid" :"a.oid") +
1929-
",c.relname,a.attname,a.atttypid," +
1930-
"a.attnum,a.attnotnull,a.attlen,a.atttypmod,d.adsrc from pg_class c," +
1931-
"pg_attribute a,pg_attrdef d where a.attrelid=c.oid and " +
1932-
"c.relname like '"+tableNamePattern.toLowerCase()+"' and " +
1933-
"a.attname like '"+columnNamePattern.toLowerCase()+"' and " +
1934-
"a.attnum>0 and c.oid=d.adrelid and d.adnum=a.attnum " +
1935-
"order by c.relname,a.attnum";
1936-
1937-
r =connection.ExecSQL(query);
1938-
1939-
while(r.next()) {
1940-
byte[][]tuple =newbyte[18][0];
1941-
1942-
// Fetch the description for the table (if any)
1943-
StringgetDescriptionStatement =
1944-
connection.haveMinimumServerVersion("7.2") ?
1945-
"select col_description(" +r.getInt(1) +"," +r.getInt(5) +")" :
1946-
"select description from pg_description where objoid=" +r.getInt(1);
1947-
1948-
java.sql.ResultSetdr =connection.ExecSQL(getDescriptionStatement);
1949-
1950-
if(((org.postgresql.ResultSet)dr).getTupleCount()==1) {
1951-
dr.next();
1952-
tuple[11] =dr.getBytes(1);
1953-
}else
1954-
tuple[11] =null;
1955-
dr.close();
1956-
1957-
tuple[0] ="".getBytes();// Catalog name
1958-
tuple[1] ="".getBytes();// Schema name
1959-
tuple[2] =r.getBytes(2);// Table name
1960-
tuple[3] =r.getBytes(3);// Column name
1961-
1962-
dr =connection.ExecSQL("select typname from pg_type where oid = "+r.getString(4));
1963-
dr.next();
1964-
Stringtypname=dr.getString(1);
1965-
dr.close();
1966-
tuple[4] =Integer.toString(connection.getSQLType(typname)).getBytes();// Data type
1967-
tuple[5] =typname.getBytes();// Type name
1968-
1969-
// Column size
1970-
// Looking at the psql source,
1971-
// I think the length of a varchar as specified when the table was created
1972-
// should be extracted from atttypmod which contains this length + sizeof(int32)
1973-
if (typname.equals("bpchar") ||typname.equals("varchar")) {
1974-
intatttypmod =r.getInt(8);
1975-
tuple[6] =Integer.toString(atttypmod != -1 ?atttypmod -VARHDRSZ :0).getBytes();
1976-
}else
1977-
tuple[6] =r.getBytes(7);
1978-
1979-
tuple[7] =null;// Buffer length
1980-
1981-
tuple[8] ="0".getBytes();// Decimal Digits - how to get this?
1982-
tuple[9] ="10".getBytes();// Num Prec Radix - assume decimal
1983-
1984-
// tuple[10] is below
1985-
// tuple[11] is above
1986-
1987-
tuple[12] =r.getBytes(9);// column default
1988-
1989-
tuple[13] =null;// sql data type (unused)
1990-
tuple[14] =null;// sql datetime sub (unused)
1920+
StringBuffersql =newStringBuffer(512);
1921+
1922+
sql.append("select " +
1923+
(connection.haveMinimumServerVersion("7.2") ?"a.attrelid, " :"a.oid, ") +
1924+
" c.relname, " +
1925+
" a.attname, " +
1926+
" a.atttypid, " +
1927+
" a.attnum, " +
1928+
" a.attnotnull, " +
1929+
" a.attlen, " +
1930+
" a.atttypmod, " +
1931+
" d.adsrc, " +
1932+
" t.typname, " +
1933+
" e.description " +
1934+
"from" +
1935+
" (" +
1936+
" (pg_class c inner join pg_attribute a on" +
1937+
" (" +
1938+
" a.attrelid=c.oid");
1939+
1940+
if ((tableNamePattern !=null) && !tableNamePattern.equals("%")) {
1941+
sql.append(" and c.relname like\'" +tableNamePattern +"\'");
1942+
}
19911943

1992-
tuple[15] =tuple[6];// char octet length
1944+
if ((columnNamePattern !=null) && !columnNamePattern.equals("%")) {
1945+
sql.append(" and a.attname like\'" +columnNamePattern +"\'");
1946+
}
19931947

1994-
tuple[16] =r.getBytes(5);// ordinal position
1948+
sql.append(
1949+
" and a.attnum > 0" +
1950+
" )" +
1951+
" ) inner join pg_type t on" +
1952+
" (" +
1953+
" t.oid = a.atttypid" +
1954+
" )" +
1955+
" )" +
1956+
" left outer join pg_attrdef d on" +
1957+
" (" +
1958+
" c.oid = d.adrelid" +
1959+
" and a.attnum = d.adnum" +
1960+
" )" +
1961+
" left outer join pg_description e on" +
1962+
" (" +
1963+
" e.objoid = a.attrelid");
1964+
1965+
if (connection.haveMinimumServerVersion("7.2")) {
1966+
sql.append(
1967+
" and e.objsubid = a.attnum" +
1968+
" and e.classoid = (select oid from pg_class where relname =\'pg_class\')");
1969+
}
19951970

1996-
StringnullFlag =r.getString(6);
1997-
tuple[10] =Integer.toString(nullFlag.equals("f")?java.sql.DatabaseMetaData.columnNullable:java.sql.DatabaseMetaData.columnNoNulls).getBytes();// Nullable
1998-
tuple[17] = (nullFlag.equals("f")?"YES":"NO").getBytes();// is nullable
1971+
sql.append(
1972+
" ) " +
1973+
"order by" +
1974+
" c.relname, a.attnum");
1975+
1976+
System.out.println(sql);
1977+
1978+
java.sql.ResultSetr =connection.ExecSQL(sql.toString());
1979+
while (r.next()) {
1980+
byte[][]tuple =newbyte[18][0];
1981+
1982+
StringnullFlag =r.getString(6);
1983+
Stringtypname =r.getString(10);
1984+
1985+
tuple[0] ="".getBytes();// Catalog name
1986+
tuple[1] ="".getBytes();// Schema name
1987+
tuple[2] =r.getBytes(2);// Table name
1988+
tuple[3] =r.getBytes(3);// Column name
1989+
tuple[4] =Integer.toString(connection.getSQLType(typname)).getBytes();// Data type
1990+
tuple[5] =typname.getBytes();// Type name
1991+
1992+
// Column size
1993+
// Looking at the psql source,
1994+
// I think the length of a varchar as specified when the table was created
1995+
// should be extracted from atttypmod which contains this length + sizeof(int32)
1996+
if (typname.equals("bpchar") ||typname.equals("varchar")) {
1997+
intatttypmod =r.getInt(8);
1998+
tuple[6] =Integer.toString(atttypmod != -1 ?atttypmod -VARHDRSZ :0).getBytes();
1999+
}else {
2000+
tuple[6] =r.getBytes(7);
2001+
}
2002+
2003+
tuple[7] =null;// Buffer length
2004+
tuple[8] ="0".getBytes();// Decimal Digits - how to get this?
2005+
tuple[9] ="10".getBytes();// Num Prec Radix - assume decimal
2006+
tuple[10] =Integer.toString(nullFlag.equals("f") ?
2007+
java.sql.DatabaseMetaData.columnNullable :
2008+
java.sql.DatabaseMetaData.columnNoNulls).getBytes();// Nullable
2009+
tuple[11] =r.getBytes(11);// Description (if any)
2010+
tuple[12] =r.getBytes(9);// Column default
2011+
tuple[13] =null;// sql data type (unused)
2012+
tuple[14] =null;// sql datetime sub (unused)
2013+
tuple[15] =tuple[6];// char octet length
2014+
tuple[16] =r.getBytes(5);// ordinal position
2015+
tuple[17] = (nullFlag.equals("f") ?"YES" :"NO").getBytes();// Is nullable
2016+
2017+
v.addElement(tuple);
2018+
}
2019+
r.close();
19992020

2000-
v.addElement(tuple);
2001-
}
2002-
r.close();
20032021
returnnewResultSet(connection,f,v,"OK",1);
20042022
}
2023+
20052024
/**
20062025
* Get a description of the access rights for a table's columns.
20072026
*

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