Issue streaming CSV-formatted data into GreenPlum using GreenPlum Streaming Server (GPSS)

Products

• VMware Tanzu Greenplum

Issue/Introduction

When streaming CSV-formatted data into Greenplum using Greenplum Streaming Server (GPSS), ingestion fails or columns are misaligned if any row is missing one or more fields (columns).

Environment

All supported Greenplum and GPSS versions

Cause

1. Fixed Mapping Requirement: GPSS configuration requires explicit, fixed column mappings.
2. CSV Parsing Limitation: CSV ingestion expects each row to contain the same number of columns, in the same order, as the header row or the target Greenplum table.
3. Rows with fewer values than columns cause errors:
1. "Missing data for column..." (input row too short)
2. "Extra data after last expected column" (input row too long).
4. Randomly missing columns across rows cannot be handled by GPSS standard CSV parsing.

Resolution

Workaround: Switch to JSON Format

1. JSON Provides Flexibility: Each record contains explicit key-value pairs; missing fields are omitted completely.
2. Configuring GPSS with JSON:
1. Set your GPSS config file format to JSON.
2. Map database columns to JSON keys by name. Missing keys in records result in NULL values.
3. Advantages:
1. Eliminates the need for preprocessing or placeholder management.
2. Handles sparse or irregular data gracefully.
3. Reduces ingestion errors and manual data cleansing requirements.

Additional Information

References:

VMware Tanzu Greenplum Streaming Server 2.x Documentation