From 9eb05a6ba40c25416e73a1381eef7ff31fcb443d Mon Sep 17 00:00:00 2001
From: Danish Sarwar <danish.sarwar@practo.com>
Date: Wed, 29 Jul 2026 23:16:51 +0530
Subject: [PATCH] fix: size bigint unsigned as numeric(20,0); commit table
 migration tx

MySQL BIGINT UNSIGNED columns propagate no source column length, so
the redshift type defaulted to numeric(18,0). Values above 10^18-1
(e.g. the int64-max sentinel 9223372036854775807) fail COPY with
"Overflow for NUMERIC(18,0)" and the loader retries the batch
forever. Size such columns to numeric(20,0), which holds the full
unsigned 64-bit range. Explicitly propagated lengths are respected.

Also fix migrateTable: when redshiftGroup was set, it returned right
after GrantSchemaAccess and skipped tx.Commit(), silently rolling
back the whole table migration. The type widening above relies on
this migration path committing.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 pkg/redshift/redshift.go             |  7 ++++++
 pkg/redshift/redshift_test.go        | 33 ++++++++++++++++++++++++++++
 pkg/redshiftloader/load_processor.go |  1 -
 3 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/pkg/redshift/redshift.go b/pkg/redshift/redshift.go
index d419acb6..ec28d4d9 100644
--- a/pkg/redshift/redshift.go
+++ b/pkg/redshift/redshift.go
@@ -1392,6 +1392,13 @@ func GetRedshiftDataType(sqlType, debeziumType, sourceColType,
 			}
 		}
 
+		// BIGINT UNSIGNED propagates no column length, and the default
+		// numeric(18,0) cannot hold its full range: COPY fails with
+		// "Overflow for NUMERIC(18,0)". Size it to 20 digits.
+		if sourceColType == "bigint unsigned" && sourceColLength == "" {
+			sourceColLength = "20"
+		}
+
 		return applyLength(
 			RedshiftToMysqlCharacterRatio,
 			redshiftType,
diff --git a/pkg/redshift/redshift_test.go b/pkg/redshift/redshift_test.go
index fa49665d..a8251706 100644
--- a/pkg/redshift/redshift_test.go
+++ b/pkg/redshift/redshift_test.go
@@ -337,6 +337,39 @@ func TestRedshiftDataTypeGet(t *testing.T) {
 			expectedResult:  "boolean",
 			expectError:     false,
 		},
+		{
+			name:            "test29: BIGINT UNSIGNED without length covers full range",
+			sqlType:         "mysql",
+			debeziumType:    "string",
+			sourceColType:   "BIGINT UNSIGNED",
+			sourceColLength: "",
+			sourceColScale:  "",
+			columnMasked:    false,
+			expectedResult:  "numeric(20,0)",
+			expectError:     false,
+		},
+		{
+			name:            "test30: BIGINT UNSIGNED with explicit length is respected",
+			sqlType:         "mysql",
+			debeziumType:    "string",
+			sourceColType:   "BIGINT UNSIGNED",
+			sourceColLength: "22",
+			sourceColScale:  "",
+			columnMasked:    false,
+			expectedResult:  "numeric(22,0)",
+			expectError:     false,
+		},
+		{
+			name:            "test31: BIGINT UNSIGNED masked stays varchar",
+			sqlType:         "mysql",
+			debeziumType:    "string",
+			sourceColType:   "BIGINT UNSIGNED",
+			sourceColLength: "",
+			sourceColScale:  "",
+			columnMasked:    true,
+			expectedResult:  "character varying(50)",
+			expectError:     false,
+		},
 	}
 
 	for _, tc := range tests {
diff --git a/pkg/redshiftloader/load_processor.go b/pkg/redshiftloader/load_processor.go
index f419c033..c75d422d 100644
--- a/pkg/redshiftloader/load_processor.go
+++ b/pkg/redshiftloader/load_processor.go
@@ -577,7 +577,6 @@ func (b *loadProcessor) migrateTable(
 		if err != nil {
 			return err
 		}
-		return err
 	}
 
 	err = tx.Commit()