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• Inserts can be done to a table or a partition. If the table is partitioned, then one must specify a specific partition of the table by specifying values for all of the partitioning columns. If hive.typecheck.on.insert is set to true, these values are validated, converted and normalized to conform to their column types (Hive 0.12.0 onward). As of HIVE-19083 there is no need to specify partition for dynamic partitions. Hive will automatically generate partition specification if user doesn't specify one. 
• Multiple insert clauses (also known as Multi Table Insert) can be specified in the same query.
• The output of each of the select statements is written to the chosen table (or partition). Currently the OVERWRITE keyword is mandatory and implies that the contents of the chosen table or partition are replaced with the output of corresponding select statement.
• The output format and serialization class is determined by the table's metadata (as specified via DDL commands on the table).
• As of Hive 0.14, if a table has an OutputFormat that implements AcidOutputFormat and the system is configured to use a transaction manager that implements ACID, then INSERT OVERWRITE will be disabled for that table.  This is to avoid users unintentionally overwriting transaction history.  The same functionality can be achieved by using TRUNCATE TABLE (for non-partitioned tables) or DROP PARTITION followed by INSERT INTO.
• As of Hive 1.1.0 the TABLE keyword is optional.
• As of Hive 1.2.0 each INSERT INTO T can take a column list like INSERT INTO T (z, x, c1).  See Description of HIVE-9481 for examples.

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In the dynamic partition inserts, users can give partial partition specifications, which means just specifying the list of partition column names in the PARTITION clause. The column values are optional. If a partition column value is given, we call this a static partition, otherwise it is a dynamic partition. Each dynamic partition column has a corresponding input column from the select statement. This means that the dynamic partition creation is determined by the value of the input column. The dynamic partition columns must be specified last among the columns in the SELECT statement and in the same order in which they appear in the PARTITION() clause. As of HIVE-19083 there is no need to specify dynamic partition columns. Hive will automatically generate partition specification if it is not specified.

Dynamic partition inserts are disabled by default prior to Hive 0.9.0 and enabled by default in Hive 0.9.0 and later. These are the relevant configuration properties for dynamic partition inserts:

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