Add Enhanced Ingestion Mode to genddl Tool

[ron-daniel1]

Adds enhanced ingestion mode to cmd/genddl for generating TPC-DS data
ingestion SQL files.

Key Features:

• Two-stage ingestion: separate source (CSV/TEXTFILE) and target (Parquet) tables
• Catalog support: multi-catalog environments with source/target catalogs
• Format handling: CSV with CAST/NULLIF, TEXTFILE with direct SELECT
• Engine support: Presto (WITH clause) and Spark (USING iceberg + TBLPROPERTIES)
• Correct schema syntax: CREATE SCHEMA catalog.schema WITH (location = 's3a://...')

Files Changed:

New Templates:

• create_source_table.sql.tmpl - Source table DDL (CSV/TEXTFILE)
• create_target_table.sql.tmpl - Target table DDL (Parquet)

Modified: main.go

Schema struct additions:

• Mode string - Detects "enhanced_ingestion" vs legacy mode
• SourceFileFormat string - "CSV" or "TEXTFILE"
• SourceSchema, TargetSchema string - Separate schema names
• SourceCatalog, TargetCatalog string - Multi-catalog support
• S3SourceLocation, S3TargetLocation string - Separate S3 paths
• Engine string - "presto" or "spark" for engine-specific syntax

New functions:

• isEnhancedIngestionMode() - Mode detection helper
• generateSourceTable() - Generates 1a-create-source-*.sql
• generateTargetTable() - Generates 1b-create-target-*.sql

Modified functions:

• loadSchemas() - In enhanced mode, generates only specified catalog type
  (iceberg=true → Iceberg only) instead of all 4 variants
• generateSchemaFromDef() - Routes to enhanced or legacy generation logic
  based on mode
• Run() - Orchestrates enhanced vs legacy workflow

Modified: insert_table.sql.tmpl

• Added conditional CAST/NULLIF for CSV: CAST(NULLIF(column, '') AS type)
• Added direct SELECT * for TEXTFILE format
• Added catalog-qualified table references: source_catalog.source_schema.table

Testing:
✅ All 10 tests pass
✅ Backward compatible - legacy mode unchanged
✅ Generated examples match golden files

Usage:
Enhanced: go run main.go genddl config_enhanced_ingestion.json
Legacy: go run main.go genddl config.json (unchanged)

[ron-daniel1]

Fix provided in PR:
Fixed typo: p_response_targe → p_response_target in 6 SQL files
Fixed partition column positioning for Iceberg tables in golden files
Fixed Go formatting with gofmt on main.go and main_test.go
Upgraded go version: go 1.26.2 → go 1.26.3

[yabinma]

Thank you @ron-daniel1 for adding/updating the PR. LGTM.

[ethanyzhang]

A few correctness/robustness notes on the enhanced ingestion mode, posted inline. (Nice work — the legacy path looks cleanly preserved.)

[ethanyzhang]

engine is accepted as "presto"/"spark" and defaulted to presto at L397, but nothing ever branches on it — grep for Engine, spark, USING, TBLPROPERTIES finds no references in any template or code path. A config with "engine": "spark" silently emits the same Presto CREATE SCHEMA ... WITH (...), USE catalog.schema, and Presto-style table DDL, contradicting the PR description's claim of Spark support (USING iceberg + TBLPROPERTIES). Suggest either rejecting non-presto engines in loadSchemas for now, or implementing the Spark template path in this PR.

[ethanyzhang]

source_file_format is unvalidated and case-sensitive. The source template treats anything != "CSV" as TEXTFILE, while insert generation (insert_table.sql.tmpl:24) treats anything != "TEXTFILE" as the CSV branch but only emits column expressions when the value is exactly "CSV". A lowercase "csv" therefore creates the source table as TEXTFILE and generates an INSERT with an empty SELECT column list (SELECT\nFROM ...) — invalid SQL, no error. Please validate source_file_format ∈ {CSV, TEXTFILE} in loadSchemas for enhanced mode.

[ethanyzhang]

This template selects enhanced vs legacy by checking .TargetSchema presence rather than .Mode. Combined with the lack of required-field validation in loadSchemas, an enhanced_ingestion config that omits target_schema runs the legacy insert branch (referencing .SchemaName, .UncompressedName, etc.) while main.go still routes through the enhanced source/target generators — producing mismatched, silently-wrong output. Suggest branching on .Mode and validating that source_schema/target_schema/s3_*_location are set up front.

[ethanyzhang]

genSubSteps is computed before the enhanced branch and the trailing if genSubSteps { generateAwsS3Mv...; generateAnalyze...; generateAwsS3Cp... } still fires in enhanced mode. An enhanced config with iceberg:false, partitioned:true would emit stray legacy 6b-s3-mv/6c-call-analyze/6d-s3-cp artifacts alongside the source/target files. Untested combo (all enhanced examples use iceberg:true), but the path is reachable and unintended — worth guarding with !schema.isEnhancedIngestionMode().