refreshTable

Invalida e aggiorna tutti i dati memorizzati nella cache e i metadati della tabella specificata.

Sintassi

refreshTable(tableName: str)

Parametri

Examples

# The example below caches a table, and then removes the data.
import tempfile
with tempfile.TemporaryDirectory(prefix="refreshTable") as d:
    _ = spark.sql("DROP TABLE IF EXISTS tbl1")
    _ = spark.sql(
        "CREATE TABLE tbl1 (col STRING) USING TEXT LOCATION '{}'".format(d))
    _ = spark.sql("INSERT INTO tbl1 SELECT 'abc'")
    spark.catalog.cacheTable("tbl1")
    spark.table("tbl1").show()
# +---+
# |col|
# +---+
# |abc|
# +---+

# Because the table is cached, it computes from the cached data as below.
spark.table("tbl1").count()
# 1

# After refreshing the table, it shows 0 because the data does not exist anymore.
spark.catalog.refreshTable("tbl1")
spark.table("tbl1").count()
# 0

# Using the fully qualified name for the table.
spark.catalog.refreshTable("spark_catalog.default.tbl1")
_ = spark.sql("DROP TABLE tbl1")