4paradigm
diff --git a/‎bazel/bison.bzl
+3-1 b/‎bazel/bison.bzl
+3-1
diff --git a/‎bazel/zetasql_deps_step_2.bzl
+23-11 b/‎bazel/zetasql_deps_step_2.bzl
+23-11
diff --git a/‎docs/aggregate_functions.md
+4-4 b/‎docs/aggregate_functions.md
+4-4
diff --git a/‎docs/approximate_aggregate_functions.md
+2 b/‎docs/approximate_aggregate_functions.md
+2
diff --git a/‎docs/array_functions.md
+124-19 b/‎docs/array_functions.md
+124-19
@@ -39,9 +39,10 @@ def _genyacc_impl(ctx):
         executable = ctx.executable._bison,
         env = {
             "M4": ctx.executable._m4.path,
+            "BISON_PKGDATADIR": ctx.files._bison_data[0].dirname,
         },
         arguments = [args],
-        inputs = ctx.files.src,
+        inputs = ctx.files._bison_data + ctx.files.src,
         tools = [ctx.executable._m4],
         outputs = outputs,
         mnemonic = "Yacc",
@@ -78,6 +79,7 @@ genyacc = rule(
             doc = "A list of extra options to pass to Bison.  These are " +
                   "subject to $(location ...) expansion.",
         ),
+        "_bison_data": attr.label(default = "@bison//:bison_runtime_data"),
         "_bison": attr.label(
             default = Label("//bazel:bison_bin"),
             executable = True,
 
@@ -106,10 +106,10 @@ cc_proto_library(
         #
         http_archive(
             name = "com_google_absl",
-            # Commit from 2020-07-01
-            url = "https://github.com/abseil/abseil-cpp/archive/81f34df8347a73c617f244f49cb916238857dc34.tar.gz",
-            sha256 = "89b1c570dd59cebf5127ff96b9b46ae8a7fe352cab4f9198e20dc7749ab8aa16",
-            strip_prefix = "abseil-cpp-81f34df8347a73c617f244f49cb916238857dc34",
+            # Commit from 2021-02-23
+            url = "https://github.com/abseil/abseil-cpp/archive/a50ae369a30f99f79d7559002aba3413dac1bd48.tar.gz",
+            sha256 = "be2a9d7ea7ee15f9317b57beff37e8ffb67418fb0df64592366b04c8618c2584",
+            strip_prefix = "abseil-cpp-a50ae369a30f99f79d7559002aba3413dac1bd48",
         )
 
     # Abseil (Python)
@@ -259,9 +259,9 @@ cc_proto_library(
         http_archive(
             name = "com_google_file_based_test_driver",
             # Commit from 2020-11-24
-            url = "https://github.com/google/file-based-test-driver/archive/5074f48f03c6a892edafab55410addc43f4a0546.tar.gz",
-            sha256 = "955cdee45433dd608bfde47d4d1dd6f47decf739a4c54cf4eecc11896dcbb374",
-            strip_prefix = "file-based-test-driver-5074f48f03c6a892edafab55410addc43f4a0546",
+            url = "https://github.com/google/file-based-test-driver/archive/77e24638ad40ec67dcbf6e37fd57e20c5d98976e.tar.gz",
+            sha256 = "fdb5d0138cc013b8b8d21b0d1827a1296621f1bfa599ef889a69eeed73a6f24b",
+            strip_prefix = "file-based-test-driver-77e24638ad40ec67dcbf6e37fd57e20c5d98976e",
         )
 
     # gRPC
@@ -467,10 +467,10 @@ cc_proto_library(
     if not native.existing_rule("junit_junit"):
         jvm_maven_import_external(
             name = "junit_junit",
-            artifact = "junit:junit:4.12",
-            tags = ["maven_coordinates=junit:junit:4.12"],
+            artifact = "junit:junit:4.13",
+            tags = ["maven_coordinates=junit:junit:4.13"],
             server_urls = ["https://repo1.maven.org/maven2"],
-            artifact_sha256 = "59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a",
+            artifact_sha256 = "4b8532f63bdc0e0661507f947eb324a954d1dbac631ad19c8aa9a00feed1d863",
             licenses = ["notice"],  # EPL 1.0
         )
 
@@ -857,10 +857,22 @@ alias(
     ##########################################################################
 
     all_content = """filegroup(name = "all", srcs = glob(["**"]), visibility = ["//visibility:public"])"""
+    bison_build_file_content = all_content + """
+filegroup(
+    name = "bison_runtime_data",
+    srcs = glob(["data/**/*"]),
+    output_licenses = ["unencumbered"],
+    path = "data",
+    visibility = ["//visibility:public"],
+
+)
+exports_files(["data"])
+
+"""
 
     http_archive(
         name = "bison",
-        build_file_content = all_content,
+        build_file_content = bison_build_file_content,
         strip_prefix = "bison-3.6.2",
         sha256 = "e28ed3aad934de2d1df68be209ac0b454f7b6d3c3d6d01126e5cd2cbadba089a",
         urls = [
 
@@ -391,11 +391,11 @@ The clauses are applied *in the following order*:
 
 <thead>
 <tr>
-<th>INPUT</th><th>INT32</th><th>INT64</th><th>UINT32</th><th>UINT64</th><th>NUMERIC</th><th>FLOAT</th><th>DOUBLE</th>
+<th>INPUT</th><th>INT32</th><th>INT64</th><th>UINT32</th><th>UINT64</th><th>NUMERIC</th><th>BIGNUMERIC</th><th>FLOAT</th><th>DOUBLE</th>
 </tr>
 </thead>
 <tbody>
-<tr><th>OUTPUT</th><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">NUMERIC</td><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">DOUBLE</td></tr>
+<tr><th>OUTPUT</th><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">NUMERIC</td><td style="vertical-align:middle">BIGNUMERIC</td><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">DOUBLE</td></tr>
 </tbody>
 
 </table>
@@ -1156,11 +1156,11 @@ The clauses are applied *in the following order*:
 
 <thead>
 <tr>
-<th>INPUT</th><th>INT32</th><th>INT64</th><th>UINT32</th><th>UINT64</th><th>NUMERIC</th><th>FLOAT</th><th>DOUBLE</th>
+<th>INPUT</th><th>INT32</th><th>INT64</th><th>UINT32</th><th>UINT64</th><th>NUMERIC</th><th>BIGNUMERIC</th><th>FLOAT</th><th>DOUBLE</th>
 </tr>
 </thead>
 <tbody>
-<tr><th>OUTPUT</th><td style="vertical-align:middle">INT64</td><td style="vertical-align:middle">INT64</td><td style="vertical-align:middle">UINT64</td><td style="vertical-align:middle">UINT64</td><td style="vertical-align:middle">NUMERIC</td><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">DOUBLE</td></tr>
+<tr><th>OUTPUT</th><td style="vertical-align:middle">INT64</td><td style="vertical-align:middle">INT64</td><td style="vertical-align:middle">UINT64</td><td style="vertical-align:middle">UINT64</td><td style="vertical-align:middle">NUMERIC</td><td style="vertical-align:middle">BIGNUMERIC</td><td style="vertical-align:middle">DOUBLE</td><td style="vertical-align:middle">DOUBLE</td></tr>
 </tbody>
 
 </table>
 
@@ -258,6 +258,8 @@ If the `weight` input is negative or `NaN`, this function returns an error.
 
 <li>NUMERIC</li>
 
+<li>BIGNUMERIC</li>
+
 <li>DOUBLE</li>
 </ul>
 
 
@@ -213,28 +213,51 @@ FROM items;
 
 ```sql
 FLATTEN(flatten_path)
+
+flatten_path:
+{
+  array_expression
+  | flatten_path.field
+  | flatten_path.array_field
+  | flatten_path.array_field[{offset_clause | safe_offset_clause}]
+}
 ```
 
 **Description**
 
-Extracts a collection of values that have the same semantic meaning from a
-tree-shaped value and returns an array. `flatten_path` is a path that can select
-many values out of the tree-shaped value and return them as an array. For
-example, `FLATTEN(table.column.array_field.target)` will return an array of all
-`targets` inside `table.column`. Tree-shaped data is represented in the
-ZetaSQL type system by composing these typed values:
-
-+ STRUCT
-+ ARRAY
-+ PROTO (Protobuf message types and enum types)
-
-The resulting array may contain `NULL` array elements, but only if
-evaluating the path along some array elements returns `NULL`. Returns `NULL`
-if `flatten_path` is `NULL`.
-
-You can learn more about flattening tree structured data into arrays and
+Nested data can be flattened into a single, flat array with the `FLATTEN`
+operator. The `FLATTEN` operator accepts a unique type of path called the
+_flatten path_. The flatten path lets you traverse through the levels of a
+nested array from left to right. For example,
+`FLATTEN(column.array_field.target)` will return an array of all
+`targets` inside `column`. The flatten path can include:
+
++ `array_expression`: Expression that evaluates to a single, flat array.
++ `flatten_path.field`: A concatenation of `element.field` for all elements of
+  `FLATTEN(flatten_path)`. `field` represents a non-array field.
++ `flatten_path.array_field`: A concatenation of elements of
+  `element.array_field` for all elements of `FLATTEN(flatten_path)`.
+  `array_field` represents an array field.
+  + `[{offset_clause | safe_offset_clause}]`: If the optional
+    [`OFFSET`][offset-clause] or [`SAFE_OFFSET`][safe-offset-clause] is present,
+    for each array_field value, `FLATTEN` includes only the array element at
+    the selected offset, rather than all elements.
+
+`FLATTEN` can return `NULL` if following the flatten path encounters a
+`NULL` before it encounters an array. Once a non-null array is encountered,
+`FLATTEN` can never return `NULL` and will always return an array.
+
+`NULL`s in arrays are added to the resulting array.
+
+Tip: Nested data is common in protocol buffers that have data within repeated
+messages.
+
+Tip: The `FLATTEN` operator is implicit inside the `UNNEST` operator and
+`UNNEST(flatten_path)` is equivalent to `UNNEST(FLATTEN(flatten_path))`.
+
+You can learn more about flattening nested data into arrays and
 the flatten path in
-[Flattening tree-structured data into arrays][flatten-tree-to-array].
+[Flattening nested data into an array][flatten-tree-to-array].
 
 **Return type**
 
@@ -313,6 +336,86 @@ SELECT FLATTEN(
 +------------------+
 ```
 
+In this example, all of the arrays for `v.sales.quantity` are concatenated in
+a flattened array.
+
+```sql
+WITH t AS (
+  SELECT
+  [
+    STRUCT([STRUCT([1,2,3] AS quantity), STRUCT([4,5,6] AS quantity)] AS sales),
+    STRUCT([STRUCT([7,8] AS quantity), STRUCT([] AS quantity)] AS sales)
+  ] AS v
+)
+SELECT FLATTEN(v.sales.quantity) AS all_values
+FROM t;
+
++--------------------------+
+| all_values               |
++--------------------------+
+| [1, 2, 3, 4, 5, 6, 7, 8] |
++--------------------------+
+```
+
+In this example, `OFFSET` gets the second value in each array and
+concatenates them.
+
+```sql
+WITH t AS (
+  SELECT
+  [
+    STRUCT([STRUCT([1,2,3] AS quantity), STRUCT([4,5,6] AS quantity)] AS sales),
+    STRUCT([STRUCT([7,8,9] AS quantity), STRUCT([10,11,12] AS quantity)] AS sales)
+  ] AS v
+)
+SELECT FLATTEN(v.sales.quantity[OFFSET(1)]) AS second_values
+FROM t;
+
++---------------+
+| second_values |
++---------------+
+| [2, 5, 8, 11] |
++---------------+
+```
+
+If you use `OFFSET` with `FLATTEN` and a value is missing from an array,
+an error is returned.
+
+```sql
+WITH t AS (
+  SELECT
+  [
+    STRUCT([STRUCT([1,2,3] AS quantity), STRUCT([4,5,6] AS quantity)] AS sales),
+    STRUCT([STRUCT([7,8,9] AS quantity), STRUCT([10] AS quantity)] AS sales)
+  ] AS v
+)
+SELECT FLATTEN(v.sales.quantity[OFFSET(1)]) AS second_values
+FROM t;
+
+-- ERROR: Array index is out of bounds.
+```
+
+In this example, `SAFE_OFFSET` gets the third value in each array and
+concatenates them. If a value is missing, a `NULL` is returned for the value.
+
+```sql
+WITH t AS (
+  SELECT
+  [
+    STRUCT([STRUCT([1,2,3] AS quantity), STRUCT([4,5,6] AS quantity)] AS sales),
+    STRUCT([STRUCT([7] AS quantity), STRUCT([10,11,12] AS quantity)] AS sales)
+  ] AS v
+)
+SELECT FLATTEN(v.sales.quantity[SAFE_OFFSET(1)]) AS third_values
+FROM t;
+
++------------------+
+| third_values     |
++------------------+
+| [3, 6, NULL, 12] |
++------------------+
+```
+
 The resulting array may contain `NULL` `ARRAY` elements, but only if
 evaluating the flatten path along some array elements returns `NULL`.
 For example:
@@ -358,7 +461,7 @@ parameters determine the inclusive start and end of the array.
 The `GENERATE_ARRAY` function accepts the following data types as inputs:
 
 <ul>
-<li>INT64</li><li>UINT64</li><li>NUMERIC</li><li>DOUBLE</li>
+<li>INT64</li><li>UINT64</li><li>NUMERIC</li><li>BIGNUMERIC</li><li>DOUBLE</li>
 </ul>
 
 The `step_expression` parameter determines the increment used to
@@ -918,11 +1021,13 @@ FROM items;
 +----------------------------------+---------------+----------------+
 ```
 
+[offset-clause]: #offset_and_ordinal
+[safe-offset-clause]: #safe_offset_and_safe_ordinal
 [subqueries]: https://github.com/google/zetasql/blob/master/docs/query-syntax.md#subqueries
 [datamodel-sql-tables]: https://github.com/google/zetasql/blob/master/docs/data-model.md#standard-sql-tables
 [datamodel-value-tables]: https://github.com/google/zetasql/blob/master/docs/data-model.md#value-tables
 [array-data-type]: https://github.com/google/zetasql/blob/master/docs/data-types.md#array_type
-[flatten-tree-to-array]: https://github.com/google/zetasql/blob/master/docs/arrays.md#flattening_trees_into_arrays
+[flatten-tree-to-array]:https://github.com/google/zetasql/blob/master/docs/arrays.md#flattening_nested_data_into_arrays
 
 [array-link-to-operators]: https://github.com/google/zetasql/blob/master/docs/operators.md