RE: JDBC driver GREATLY speeded up by trivial fix
От | William Chesters |
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Тема | RE: JDBC driver GREATLY speeded up by trivial fix |
Дата | |
Msg-id | 14725.12859.857141.405432@beertje.william.bogus обсуждение исходный текст |
Ответ на | RE: JDBC driver GREATLY speeded up by trivial fix (Peter Mount <petermount@it.maidstone.gov.uk>) |
Список | pgsql-interfaces |
Peter Mount writes:> As for receiveString(), it predates the driver merger (some 2 years ago?) so> as it's never broke it'sbeen left. I suspect there's a lot of little> performace gems in there if we had time to sit down and do them. Well, nothing else really leaps out the profiling data. It looks like the effect of further improvements will be relatively marginal compared with the unavoidable time spent on socket reads/writes, and of course waiting for the backend to do its stuff. > I'm currently having horrible problems with my home system (hasn't recovered> well after the move) sympathy ... If you gave me a CVS p/w I could apply the ReceiveString fix and my private fix for getTimestamp?? By the way, I've also got a rough implementation of DatabaseMetaData.getIndexInfo---appended, with test harness---which certainly does something, whether the JDBC-ly correct thing I don't know! Thanks, William public java.sql.ResultSet getIndexInfo(String catalog, String schema, String table,boolean unique, boolean approximate) throws java.sql.SQLException { return ((Connection)getConnection()).ExecSQL( "SELECT " + "null AS TABLE_CAT, null AS TABLE_SCHEMA, t.relnameAS TABLE_NAME, " + "NOT i.indisunique AS NON_UNIQUE, null AS INDEX_QUALIFIER, " + "ti.relname ASINDEX_NAME, " + tableIndexOther + " AS TYPE, " + "i.indkey[0] AS ORDINAL_POSITION, a.attname AS COLUMN_NAME, "+ "NULL AS ASC_OR_DESC, 0 AS CARDINALITY, 0 AS PAGES, " + "NULL AS FILTER_CONDITION " + "FROM " + "pg_index i, pg_class ti, pg_class t, pg_attribute a " + "WHERE " + "ti.oid = i.indexrelid AND t.oid= i.indrelid AND " + (table == null ? "" : "t.relname = '" + StringUtils.escaped(table,'\'') + "' AND ") + (unique ? "i.indisunique AND " : "") + "a.attrelid = i.indrelidAND " + // this strange little construct is needed because // `a.attnum = i.indkey[0]' causes 6.4.2(at least) to fail, losing // connection to backend: "a.attnum - i.indkey[0] = 0"); } public static void main(String[] args) throws Exception { java.sql.DriverManager.registerDriver((Driver)Class.forName("postgresql.Driver").newInstance()); java.sql.Connection c =java.sql.DriverManager.getConnection("jdbc:postgresql:" + args[0], "postgres", "*"); java.sql.DatabaseMetaData m = c.getMetaData(); java.sql.ResultSet inds = m.getIndexInfo(null, "", args[1], false, true); while (inds.next()) System.out.println("TABLE_CAT" + inds.getString("TABLE_CAT") + "\n" + "TABLE_SCHEMA " + inds.getString("TABLE_SCHEMA")+ "\n" + "TABLE_NAME " + inds.getString("TABLE_NAME") + "\n" + "NON_UNIQUE " + inds.getBoolean("NON_UNIQUE") + "\n" + "INDEX_QUALIFIER " + inds.getString("INDEX_QUALIFIER")+ "\n" + "INDEX_NAME " + inds.getString("INDEX_NAME") + "\n" + "TYPE " + inds.getShort("TYPE") + "\n" + "ORDINAL_POSITION " + inds.getShort("ORDINAL_POSITION")+ "\n" + "COLUMN_NAME " + inds.getString("COLUMN_NAME") + "\n" + "ASC_OR_DESC " + inds.getString("ASC_OR_DESC") + "\n" + "CARDINALITY " + inds.getInt("CARDINALITY")+ "\n" + "PAGES " + inds.getInt("PAGES") + "\n" + "FILTER_CONDITION " + inds.getString("FILTER_CONDITION") + "\n"); }
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