sspl-main-table¶
Date: 2026-09-12. Status: implemented.
Decision. Two tables from two NRS products. The main table, postcode_simd.parquet, is built from the Scottish Statistics Postcode Lookup (SSPL): one row per whole postcode, both user types, latest life including deleted postcodes, key pc_norm. The history table, postcode_simd_history.parquet, is the existing SPD build: every postcode life, key (pc_norm, introduced_on), rows unchanged. Neither table is derived from the other.
Reason. NRS recommends SSPL for statistical production. History is still needed for date-valid postcode matching and inspecting split parts. Choosing an SIMD edition by event year does not itself require postcode history: the default SQL era query reads SSPL.
Evidence. docs/plans/SSPL_Main_Table_Plan.md section 1: SSPL 2026/1 has 229,708 unique whole postcodes, both data-zone vintages, no blank geography, PO-box sentinels, and deletion dates.
Columns (55): CensusHouseholdCount1991, CensusHouseholdCount2001, CensusHouseholdCount2011, CensusHouseholdCount2022, CensusPopulationCount1991, CensusPopulationCount2001, CensusPopulationCount2011, CensusPopulationCount2022, CivilParish1930Code, CouncilArea2019Code, DataZone2001Code, DataZone2011Code, DataZone2022Code, DateOfDeletion, DateOfIntroduction, ElectoralWard2022Code, GridReferenceEasting, GridReferenceNorthing, HealthBoardArea1995Code, HealthBoardArea2006Code, HealthBoardArea2019Code, ITL2025Level2Code, ITL2025Level3Code, IntegrationAuthority2019Code, IntermediateZone2001Code, IntermediateZone2011Code, IntermediateZone2022Code, IslandCode, LAU2025Level1Code, LinkedSmallUserPostcode, LocalGovernmentDistrict1991Code, LocalGovernmentDistrict1995Code, OutputArea1991Code, OutputArea2001Code, OutputArea2011Code, OutputArea2022Code, Postcode, PostcodeDistrict, PostcodeSector, PostcodeType, RegistrationDistrict2007Code, ScottishIndexOfMultipleDeprivation2020Rank, ScottishParliamentaryConstituency2026Code, ScottishParliamentaryRegion2026Code, SplitIndicator, StrategicDevelopmentPlanningArea2013Code, TravelToWorkArea2011Code, UKParliamentaryConstituency2024Code, UrbanRural6Fold2022Code, UrbanRural8Fold2022Code, deleted_on, introduced_on, is_current, pc_norm, spd_user_type