getOrCreateDataIndex
Retrieves an existing data index for a given table and specified key column(s), or creates the index if it does not already exist.
This method is part of the io.deephaven.engine.table.impl.indexer.DataIndexer class and is typically used via a static import.
Syntax
index = getOrCreateDataIndex(someTable, "KeyColumn1")
index = getOrCreateDataIndex(someTable, "KeyColumn1", "KeyColumn2")
index = getOrCreateDataIndex(someTable, ["KeyColumn1", "KeyColumn2"] as String[])
Parameters
| Parameter | Type | Description |
|---|---|---|
| table | Table | The table from which to retrieve or create the data index. |
| keyColumnNames | String... | The name(s) of the key column(s) defining the index (varargs). |
| keyColumnNames | String[] | The name(s) of the key column(s) defining the index (array). |
Returns
Returns the existing or newly created DataIndex object.
Examples
import static io.deephaven.engine.table.impl.indexer.DataIndexer.getOrCreateDataIndex
import static io.deephaven.engine.table.impl.indexer.DataIndexer.hasDataIndex
// Create a source table
def sourceTable = emptyTable(100).update(
"Category = \"Cat\" + (int)(i % 4)",
"ID = i"
)
// Check if an index exists on Category (it doesn't yet)
println "Has index on Category BEFORE: ${hasDataIndex(sourceTable, "Category")}" // Output: false
// Get or create an index on Category
def indexCategory = getOrCreateDataIndex(sourceTable, "Category")
println "Index on Category: ${indexCategory}" // Output: (DataIndex object)
// Check if an index exists on Category (it does now)
println "Has index on Category AFTER: ${hasDataIndex(sourceTable, "Category")}" // Output: true
// Get or create an index on Category and ID
def indexCategoryId = getOrCreateDataIndex(sourceTable, "Category", "ID")
println "Index on Category, ID: ${indexCategory}" // Output: (DataIndex object)
println "Has index on Category, ID: ${hasDataIndex(sourceTable, "Category", "ID")}" // Output: true