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SNOW-805980: Show Pagination POC at JDBC driver level #1502

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SNOW-805980: Show Pagination POC at JDBC driver level #1502

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9ea838e
Show Pagination Driver level POC
sfc-gh-abakare Aug 28, 2023
ecc2956
removing formatting changes
sfc-gh-abakare Aug 29, 2023
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106 changes: 70 additions & 36 deletions src/main/java/net/snowflake/client/jdbc/SnowflakeDatabaseMetaData.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1498,6 +1498,8 @@ public ResultSet getTables(
}
}

// adding this just for POC purpose.
showTablesCommand += " limit 1";
logger.debug("sql command to get table metadata: {}", showTablesCommand);

resultSet = executeAndReturnEmptyResultIfNotFound(statement, showTablesCommand, GET_TABLES);
Expand All @@ -1510,51 +1512,83 @@ public ResultSet getTables(
Arrays.toString(types));

return new SnowflakeDatabaseMetaDataQueryResultSet(GET_TABLES, resultSet, statement) {

// maintain last table which was returned to use this information for next pagination call
String lastTable = null;

@Override
public boolean next() throws SQLException {
logger.debug("public boolean next()", false);
incrementRow();

// iterate throw the show table result until we find an entry
// that matches the table name
// get the next table
while (showObjectResultSet.next()) {
String tableName = showObjectResultSet.getString(2);

String dbName;
String schemaName;
String kind;
String comment;

if (viewOnly) {
dbName = showObjectResultSet.getString(4);
schemaName = showObjectResultSet.getString(5);
kind = "VIEW";
comment = showObjectResultSet.getString(7);
} else {
dbName = showObjectResultSet.getString(3);
schemaName = showObjectResultSet.getString(4);
kind = showObjectResultSet.getString(5);
comment = showObjectResultSet.getString(6);
}
if (createRow()) return true;
}

if ((compiledTablePattern == null || compiledTablePattern.matcher(tableName).matches())
&& (compiledSchemaPattern == null
|| compiledSchemaPattern.matcher(schemaName).matches())) {
nextRow[0] = dbName;
nextRow[1] = schemaName;
nextRow[2] = tableName;
nextRow[3] = kind;
nextRow[4] = comment;
nextRow[5] = null;
nextRow[6] = null;
nextRow[7] = null;
nextRow[8] = null;
nextRow[9] = null;
return true;
}
// if no more results are found, now trigger pagination call
// Note: In actuality, instead of show tables command, a pagination call with a token will be invoked here.
// For now, a show command is invoked.
ResultSet resultSet1 = executeAndReturnEmptyResultIfNotFound(statement, "show /* JDBC:DatabaseMetaData.getTables() */ tables in schema \"JDBC_DB1\".\"JDBC_SCHEMA11\" limit 1 from '" + lastTable + "'", GET_TABLES);
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@sfc-gh-igarish sfc-gh-igarish Aug 30, 2023 •
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This won't work everytime, if table list change after getting first set of values. Do we have any design doc or something like that? Let's review that before you make code changes. If we don't have any doc, please start a doc first.

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+1 to what Ilesh said. It would be great to see a one pager that first outlines what is it that we're trying to achieve and how we're thinking of doing it. Looking at code is great but it does not give the big picture.

sendInBandTelemetryMetadataMetrics(
resultSet1,
"getTables",
originalCatalog,
originalSchemaPattern,
tableNamePattern,
Arrays.toString(types));
this.showObjectResultSet = resultSet1;

// get first result from pagination call and return it as a part of next()
boolean foundAnyObject = false;
while (showObjectResultSet.next()) {
foundAnyObject = true;
if (createRow()) return true;
}

// if no results are found out of pagination, that means all objects are found. Close the ResultSet and show is done.
if (!foundAnyObject) {
close();
return false;
}
return true;
}

private boolean createRow() throws SQLException {
String tableName = showObjectResultSet.getString(2);

String dbName;
String schemaName;
String kind;
String comment;

if (viewOnly) {
dbName = showObjectResultSet.getString(4);
schemaName = showObjectResultSet.getString(5);
kind = "VIEW";
comment = showObjectResultSet.getString(7);
} else {
dbName = showObjectResultSet.getString(3);
schemaName = showObjectResultSet.getString(4);
kind = showObjectResultSet.getString(5);
comment = showObjectResultSet.getString(6);
}

close(); // close
if ((compiledTablePattern == null || compiledTablePattern.matcher(tableName).matches())
&& (compiledSchemaPattern == null
|| compiledSchemaPattern.matcher(schemaName).matches())) {
nextRow[0] = dbName;
nextRow[1] = schemaName;
nextRow[2] = lastTable = tableName;
nextRow[3] = kind;
nextRow[4] = comment;
nextRow[5] = null;
nextRow[6] = null;
nextRow[7] = null;
nextRow[8] = null;
nextRow[9] = null;
return true;
}
return false;
}
};
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