Fokko commented on code in PR #9935:
URL: https://github.com/apache/iceberg/pull/9935#discussion_r1521056978
##########
1.5.0/docs/spark-getting-started.md:
##########
@@ -123,18 +123,78 @@ SELECT * FROM local.db.table.snapshots;
+-------------------------+----------------+-----------+-----------+----------------------------------------------------+-----+
```
-[DataFrame reads](spark-queries.md#querying-with-dataframes) are supported and
can now reference tables by name using `spark.table`:
+[DataFrame reads](../spark-queries.md#querying-with-dataframes) are supported
and can now reference tables by name using `spark.table`:
```scala
val df = spark.table("local.db.table")
df.count()
```
+### Type compatibility
+
+Spark and Iceberg support different set of types. Iceberg does the type
conversion automatically, but not for all combinations,
+so you may want to understand the type conversion in Iceberg in prior to
design the types of columns in your tables.
+
+#### Spark type to Iceberg type
+
+This type conversion table describes how Spark types are converted to the
Iceberg types. The conversion applies on both creating Iceberg table and
writing to Iceberg table via Spark.
+
+| Spark | Iceberg | Notes |
+|-----------------|----------------------------|-------|
+| boolean | boolean | |
+| short | integer | |
+| byte | integer | |
+| integer | integer | |
+| long | long | |
+| float | float | |
+| double | double | |
+| date | date | |
+| timestamp | timestamp with timezone | |
+| timestamp_ntz | timestamp without timezone | |
Review Comment:
OCD
```suggestion
| timestamp_ntz | timestamp without timezone | |
```
##########
1.5.0/docs/spark-getting-started.md:
##########
@@ -123,18 +123,78 @@ SELECT * FROM local.db.table.snapshots;
+-------------------------+----------------+-----------+-----------+----------------------------------------------------+-----+
```
-[DataFrame reads](spark-queries.md#querying-with-dataframes) are supported and
can now reference tables by name using `spark.table`:
+[DataFrame reads](../spark-queries.md#querying-with-dataframes) are supported
and can now reference tables by name using `spark.table`:
```scala
val df = spark.table("local.db.table")
df.count()
```
+### Type compatibility
+
+Spark and Iceberg support different set of types. Iceberg does the type
conversion automatically, but not for all combinations,
+so you may want to understand the type conversion in Iceberg in prior to
design the types of columns in your tables.
+
+#### Spark type to Iceberg type
+
+This type conversion table describes how Spark types are converted to the
Iceberg types. The conversion applies on both creating Iceberg table and
writing to Iceberg table via Spark.
+
+| Spark | Iceberg | Notes |
+|-----------------|----------------------------|-------|
+| boolean | boolean | |
+| short | integer | |
+| byte | integer | |
+| integer | integer | |
+| long | long | |
+| float | float | |
+| double | double | |
+| date | date | |
+| timestamp | timestamp with timezone | |
+| timestamp_ntz | timestamp without timezone | |
+| char | string | |
+| varchar | string | |
+| string | string | |
+| binary | binary | |
+| decimal | decimal | |
+| struct | struct | |
+| array | list | |
+| map | map | |
+
+!!! info
+ The table is based on representing conversion during creating table. In
fact, broader supports are applied on write. Here're some points on write:
+
+ * Iceberg numeric types (`integer`, `long`, `float`, `double`, `decimal`)
support promotion during writes. e.g. You can write Spark types `short`,
`byte`, `integer`, `long` to Iceberg type `long`.
+ * You can write to Iceberg `fixed` type using Spark `binary` type. Note
that assertion on the length will be performed.
+
+#### Iceberg type to Spark type
+
+This type conversion table describes how Iceberg types are converted to the
Spark types. The conversion applies on reading from Iceberg table via Spark.
+
+| Iceberg | Spark | Note |
+|----------------------------|-------------------------|---------------|
+| boolean | boolean | |
+| integer | integer | |
+| long | long | |
+| float | float | |
+| double | double | |
+| date | date | |
+| time | | Not supported |
+| timestamp with timezone | timestamp | |
+| timestamp without timezone | timestamp_ntz | |
Review Comment:
```suggestion
| timestamp without timezone | timestamp_ntz | |
```
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