Databricks - is not empty but it's not a Delta table

Solution 1:

DROP TABLE & CREATE TABLE work with entries in the Metastore that is some kind of database that keeps the metadata about databases and tables. There could be the situation when entries in metastore don't exist so DROP TABLE IF EXISTS doesn't do anything. But when CREATE TABLE is executed, then it additionally check for location on DBFS, and fails if directory exists (maybe with data). This directory could be left from some previous experiments, when data were written without using the metastore.

Solution 2:

if the table created with LOCATION specified - this means the table is EXTERNAL, so when you drop it - you drop only hive metadata for that table, directory contents remains as it is. You can restore the table by CREATE TABLE if you specify the same LOCATION (Delta keeps table structure along with it's data in the directory).

if LOCATION wasn't specified while table creation - it's a MANAGED table, DROP will destroy metadata and directory contents

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