KustoCodeExtensions.md

KustoCode Extensions

These extension methods add additional functionality to your KustoCode instances.

KustCode.GetDatabaseTablesReferenced()

Returns a list of all the database tables that are explicitly referenced in the query. This includes any table named explicitly or via the table() function, both in the body of the query and inside any function the query calls.

var code = KustoCode.ParseAndAnalyze("TableA | join TableB on Id", globals);
var tables = code.GetDatabaseTablesReferenced();
// tables: TableA, TableB

KustoCode.GetDatabaseTableColumnsReferenced()

Returns a list of all the database table columns explicitly referenced in the query. This includes any column referencd in the body of the query and inside any function the query calls.

var code = KustoCode.ParseAndAnalyze("TableA | where X > Y | project A, B, C", globals);
var columns = code.GetDatabaseTablesReferenced();
// columns: X, Y, A, B, C

KustoCode.GetDatabaseTableColumnsInResult()

Returns a list of only the database table columns in the query result, which may be different than all the columns in the query result since the result may contain computed columns.

var code = KustoCode.ParseAndAnalyze("TableA | where X > Y | project A, B, V=C*D", globals);
var columns = code.GetDatabaseTablesColumnsInResult();
// columns: A, B

KustoCode.GetResultColumns()

Returns all the columns in the result of the query.

// TableA: A, B, C, D, X, Y, Z
var code = KustoCode.ParseAndAnalyze("TableA | where X > Y | extend V=C*D", globals);
var columns = code.GetResultColumns();
// columns: A, B, C, D, X, Y, Z, V

KustoCode.GetSourceColumns()

Returns the set of database table columns that contributed to the data contained in the result columns.

var code = KustoCode.ParseAndAnalyze("TableA | where X > Y | project AB=A+B, CD=C+D", globals);
var columns = code.GetSourceColumns();
// columns: A, B, C, D

KustoCode.GetSourceColumns(ColumnSymbol column)

Returns the set of database table columns that contributed to the data contained in the specified column.

var code = KustoCode.ParseAndAnalyze("TableA | where X > Y | project AB=A+B, CD=C+D", globals);
var resultColumn = code.GetResultColumns().First(c => c.Name == "AB");
var columns = code.GetSourceColumns(resultColumn);
// columns: A, B

KustoCode.GetSourceColumns(IReadOnlyList<ColumnSymbol> columns)

Returns the set of database table columns that contributed to the data contained in the specified columns.

var code = KustoCode.ParseAndAnalyze("TableA | where X > Y | project AB=A+B, AC=A+C, BC=B+C", globals);
var resultColumns = code.GetResultColumns().First(c => c.Name.StartsWith("A")).ToList();
var columns = code.GetSourceColumns(resultColumns);
// columns: A, B, C

KustoCode.GetSourceColumnMap()

Returns the a map between the query's result columns and the set of database table columns that contributed to them.

var code = KustoCode.ParseAndAnalyze("TableA | where X > Y | project AB=A+B, AC=A+C, BC=B+C", globals);
var map = code.GetSourceColumnMap();
// map: AB: [A, B], AC: [A, C], BC: [B, C]

KustoCode.GetSourceColumnMap(IReadOnlyList<ColumnSymbol> columns)

Returns the a map between the specified columns and the set of database table columns that contributed to them.

var code = KustoCode.ParseAndAnalyze("TableA | where X > Y | project AB=A+B, AC=A+C, BC=B+C", globals);
var resultColumns = code.GetResultColumns().First(c => c.Name.StartsWith("A")).ToList();
var columns = code.GetSourceColumnMap(resultColumns);
// map: AB: [A, B], AC: [A, C]

Not extensions, but still useful

GetDatabaseTableColumnsReferenced(SyntaxNode root, GlobalState globals)

This is a non-extension version of GeDatabaseTableColumns() that you can use to discover the columns referenced in a sub-tree of the entire query.

var code = KustoCode.ParseAndAnalyze("TableA | where X > Y | project A, B, C", globals);
// only get database table columns referenced in the project operator 
var projectNode = code.GetFirstDescendant<ProjectOperator>();
var columns = KustoExtensions.GetDatabaseTableColumnsReferenced(projectNode, code.Globals);
// columns: A, B, C

GetColumnsReferenced(SyntaxNode node)

Returns a list of all columns referenced or declared in the sub-tree, or inside any function called within the sub-tree.

var code = KustoCode.ParseAndAnalyze("TableA | extend YY=Y*Y | where X > YY | project A, B, C", globals);
// only get columns referenced in the where/filter operator
var whereNode = code.GetFirstDescendant<FilterOperator>();
var columns = KustoExtensions.GetColumnsReferenced(projectNode);
// columns: X, YY