1 files changed, 184 insertions, 0 deletions
diff --git a/src/arrow/go/parquet/metadata/app_version.go b/src/arrow/go/parquet/metadata/app_version.go
new file mode 100644
index 000000000..1433da400
--- /dev/null
+++ b/src/arrow/go/parquet/metadata/app_version.go
@@ -0,0 +1,184 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metadata
+
+import (
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/apache/arrow/go/v6/parquet"
+	"github.com/apache/arrow/go/v6/parquet/schema"
+)
+
+var (
+	// Regular expression for the version format
+	// major . minor . patch unknown - prerelease.x + build info
+	// Eg: 1.5.0ab-cdh5.5.0+cd
+	versionRx = regexp.MustCompile(`^(\d+)\.(\d+)\.(\d+)([^-+]*)?(?:-([^+]*))?(?:\+(.*))?$`)
+	// Regular expression for the application format
+	// application_name version VERSION_FORMAT (build build_name)
+	// Eg: parquet-cpp version 1.5.0ab-xyz5.5.0+cd (build abcd)
+	applicationRx = regexp.MustCompile(`^(.*?)\s*(?:(version\s*(?:([^(]*?)\s*(?:\(\s*build\s*([^)]*?)\s*\))?)?)?)$`)
+
+	// Parquet816FixedVersion is the version used for fixing PARQUET-816
+	// that changed the padding calculations for dictionary headers on row groups.
+	Parquet816FixedVersion      = NewAppVersionExplicit("parquet-mr", 1, 2, 9)
+	parquet251FixedVersion      = NewAppVersionExplicit("parquet-mr", 1, 8, 0)
+	parquetCPPFixedStatsVersion = NewAppVersionExplicit("parquet-cpp", 1, 3, 0)
+	parquetMRFixedStatsVersion  = NewAppVersionExplicit("parquet-mr", 1, 10, 0)
+	// parquet1655FixedVersion is the version used for fixing PARQUET-1655
+	// which fixed min/max stats comparisons for Decimal types
+	parquet1655FixedVersion = NewAppVersionExplicit("parquet-cpp-arrow", 4, 0, 0)
+)
+
+// AppVersion represents a specific application version either read from
+// or written to a parquet file.
+type AppVersion struct {
+	App     string
+	Build   string
+	Version struct {
+		Major      int
+		Minor      int
+		Patch      int
+		Unknown    string
+		PreRelease string
+		BuildInfo  string
+	}
+}
+
+// NewAppVersionExplicit is a convenience function to construct a specific
+// application version from the given app string and version
+func NewAppVersionExplicit(app string, major, minor, patch int) *AppVersion {
+	v := &AppVersion{App: app}
+	v.Version.Major = major
+	v.Version.Minor = minor
+	v.Version.Patch = patch
+	return v
+}
+
+// NewAppVersion parses a "created by" string such as "parquet-go 1.0.0".
+//
+// It also supports handling pre-releases and build info such as
+// 	parquet-cpp version 1.5.0ab-xyz5.5.0+cd (build abcd)
+func NewAppVersion(createdby string) *AppVersion {
+	v := &AppVersion{}
+
+	var ver []string
+
+	m := applicationRx.FindStringSubmatch(strings.ToLower(createdby))
+	if len(m) >= 4 {
+		v.App = m[1]
+		v.Build = m[4]
+		ver = versionRx.FindStringSubmatch(m[3])
+	} else {
+		v.App = "unknown"
+	}
+
+	if len(ver) >= 7 {
+		v.Version.Major, _ = strconv.Atoi(ver[1])
+		v.Version.Minor, _ = strconv.Atoi(ver[2])
+		v.Version.Patch, _ = strconv.Atoi(ver[3])
+		v.Version.Unknown = ver[4]
+		v.Version.PreRelease = ver[5]
+		v.Version.BuildInfo = ver[6]
+	}
+	return v
+}
+
+// LessThan compares the app versions and returns true if this version
+// is "less than" the passed version.
+//
+// If the apps don't match, this always returns false. Otherwise it compares
+// the major versions first, then the minor versions, and finally the patch
+// versions.
+//
+// Pre-release and build info are not considered.
+func (v AppVersion) LessThan(other *AppVersion) bool {
+	switch {
+	case v.App != other.App:
+		return false
+	case v.Version.Major < other.Version.Major:
+		return true
+	case v.Version.Major > other.Version.Major:
+		return false
+	case v.Version.Minor < other.Version.Minor:
+		return true
+	case v.Version.Minor > other.Version.Minor:
+		return false
+	}
+
+	return v.Version.Patch < other.Version.Patch
+}
+
+// Equal only compares the Application and major/minor/patch versions.
+//
+// Pre-release and build info are not considered.
+func (v AppVersion) Equal(other *AppVersion) bool {
+	return v.App == other.App &&
+		v.Version.Major == other.Version.Major &&
+		v.Version.Minor == other.Version.Minor &&
+		v.Version.Patch == other.Version.Patch
+}
+
+// HasCorrectStatistics checks whether or not the statistics are valid to be used
+// based on the primitive type and the version since previous versions had issues with
+// properly computing stats.
+//
+// Reference: parquet-cpp/src/parquet/metadata.cc
+//
+// PARQUET-686 has more discussion on statistics
+func (v AppVersion) HasCorrectStatistics(coltype parquet.Type, logicalType schema.LogicalType, stats EncodedStatistics, sort schema.SortOrder) bool {
+	// parquet-cpp version 1.3.0 and parquet-mr 1.10.0 onwards stats are computed correctly for all types except decimal
+	if (v.App == "parquet-cpp" && v.LessThan(parquetCPPFixedStatsVersion)) ||
+		(v.App == "parquet-mr" && v.LessThan(parquetMRFixedStatsVersion)) {
+		// only SIGNED are valid unless max and min are the same (in which case the sort order doesn't matter)
+		var maxEqualsMin bool
+		if stats.HasMin && stats.HasMax {
+			maxEqualsMin = string(stats.Min) == string(stats.Max)
+		}
+		if sort != schema.SortSIGNED && !maxEqualsMin {
+			return false
+		}
+
+		if coltype != parquet.Types.FixedLenByteArray && coltype != parquet.Types.ByteArray {
+			return true
+		}
+	}
+
+	// parquet-cpp-arrow version 4.0.0 fixed Decimal comparisons for creating min/max stats
+	// parquet-cpp also becomes parquet-cpp-arrow as of version 4.0.0
+	if v.App == "parquet-cpp" || (v.App == "parquet-cpp-arrow" && v.LessThan(parquet1655FixedVersion)) {
+		if _, ok := logicalType.(*schema.DecimalLogicalType); ok && coltype == parquet.Types.FixedLenByteArray {
+			return false
+		}
+	}
+
+	// created_by is not populated, which could have been caused by
+	// parquet-mr during the same time as PARQUET-251, see PARQUET-297
+	if v.App == "unknown" {
+		return true
+	}
+
+	// unknown sort order has incorrect stats
+	if sort == schema.SortUNKNOWN {
+		return false
+	}
+
+	// PARQUET-251
+	return !v.LessThan(parquet251FixedVersion)
+}