Database Reference

Summary

This document describes the Velox database architecture as implemented in the velox repository. It covers logical databases, connection configuration, connection pooling, module persistence, major tables, relationships, indexes, and migrations.

The source code is the authority for this document. Where behavior could not be determined from the reviewed code, it is marked as unclear.

Related PKB Documents

• Architecture
• Domain Model
• Developer Guide
• Configuration Reference
• Flow Execution
• Logging Reference
• Error Reference
• API Reference
• Technical Debt

Source Code Locations

Area	Source location
System connection model	Classes/vxCon.pas
System DB data module	Classes/dmSystemDB.pas
Database connection parameters	Classes/vxDBParams.pas
SQL connection wrapper	Classes/vxSQLConnection.pas
System connection pool	Classes/vxConPool.pas
DB Connection pool	Classes/vxSQLConPool.pas
SQL builder and schema helper	Classes/vxSQL.pas
Database upgrade controller	Classes/GUI/vxDBUpdate.pas
Database upgrade versions	Classes/GUI/vxDBUpdateVersion.pas
Database upgrade form	Forms/frmDatabaseUpgrade.pas
Base module persistence	Classes/vxModule.pas
Setup persistence	Classes/vxSetup.pas
Flow persistence	Classes/vxActionMan.pas
API persistence	Classes/vxAPI.pas
DB Connection persistence	Classes/vxDBCon.pas
DB Definition persistence	Classes/vxDBDef.pas
File Connection persistence	Classes/vxFileCon.pas
File Definition persistence	Classes/vxFileDef.pas
Folder persistence	Classes/vxFolder.pas
Map persistence	Classes/vxMap.pas
Report persistence	Classes/vxReport.pas
SQL Script persistence	Classes/vxSQLScript.pas
Scriptlet persistence	Classes/vxScriptlet.pas
Variable persistence	Classes/vxVariableGroup.pas
Module relation sync utility	Forms/frmModuleSync.pas, Classes/GUI/vxModuleSync.pas
FID lookup helpers	Classes/Tools/vxFID.pas
Constants and current database version	Classes/Tools/vxConstant.pas

Important Classes, Forms, and Services

Type	Name	Purpose
Class	TvxConnection	Loads Connections.json, selects active production/test config, log, and data databases, and provides SQLC, SQLL, and SQLD accessors.
Class	TvxDBParams	Holds one database connection definition: host type, host, database name, authentication, username, encrypted password, driver, and certificate trust flag.
Class	TvxSQLConnection	TSQLConnection descendant that applies Velox connection parameters, wraps transactions, tracks owning thread, and integrates with connection pools.
Class	TvxSysConPool / TvxSysConItem	Thread-aware connection pool for system config/log/data databases.
Class	TvxSQLConPool / TvxSQLConItem	Thread-aware connection pool for user-configured DB Connections.
Class	TvxSystemDB	Per-module data module that creates config/log/data queries and binds ReportBuilder pipelines for module template persistence.
Class	TvxSQL	SQL builder and DDL/DML helper used by migrations and module utilities.
Class	TVxDBUpdate	Checks database version and orchestrates version upgrade threads.
Class	TVxDBUpdateVersion*	One migration thread per database version.
Class	TvxModule	Base class for most persisted Velox modules.
Class	TvxModuleTemplate	ReportBuilder template wrapper used to serialize/deserialize module component graphs.
Class	TvxLog	Runtime log module persisted to VX_LOG and related log tables.
Form	TDatabaseUpgrade	Modal database upgrade UI shown when the database version is behind the Velox MajorVersion.
Form	TModuleSync	Maintenance UI that creates and uses VX_REFS while rebuilding module references.
Service	VeloxService	Loads database configuration at service startup and uses the same connection/persistence layer. It does not run the reviewed database upgrade check.
Service	VeloxAPIService	Loads database configuration at API service startup and uses the same connection/persistence layer. It does not run the reviewed database upgrade check.

Overall Database Architecture

Velox separates database usage into three logical roles:

Logical database	Accessor	Purpose	Source-observed behavior
Config database	gSystemConnection.SQLC / TvxSystemDB.NewConfigQuery	Stores Velox configuration modules, setup, flows, definitions, maps, transports, APIs, variables, and migration version.	Primary source of module configuration.
Log database	gSystemConnection.SQLL / TvxSystemDB.NewLogQuery	Intended to store runtime logs.	In reviewed code, SQLL currently returns SQLC; comments state duplicate log connections are not used yet.
Data database	gSystemConnection.SQLD / TvxSystemDB.NewDataQuery	Represents the active Velox data database used by runtime/data processing.	The Velox repository references the connection, but the VxData schema itself is outside the reviewed Velox system schema migration code.

Each logical role has production and test connection definitions:

• Config and ConfigTest
• Log and LogTest
• Data and DataTest

TvxConnection.TestMode chooses the active production or test set. SwitchSystemConnectionMode changes the mode and clears system/user connection pools.

Database Architecture Diagram

Database Platform Support

The type definitions list these database connection types:

• Microsoft SQL Server
• Oracle
• MySQL
• PostgreSQL
• IBM DB2
• ADO
• ODBC

However, the reviewed TvxSQLConnection.VxConnect implementation only shows concrete runtime parameter setup for ctMSSQL. The schema builder in TvxSQL also uses SQL Server system views and syntax such as sys.tables, sys.columns, sys.indexes, uniqueidentifier, GETDATE(), SCOPE_IDENTITY(), and sp_rename.

Therefore:

• The Velox system/config/log schema migration path is SQL Server-specific in the reviewed code.
• The DB Connection feature exposes broader database types for user data connections and ReportBuilder data settings.
• Full runtime support for non-SQL Server database types cannot be confirmed from the reviewed connection implementation alone.

Configuration Loading

Database configuration is loaded from Connections.json under AppDataConfigPath.

TvxConnection.Create parses the JSON file, loads the Databases collection into TvxDBParams objects, and TvxConnection.Load selects one item from Connections.

JSON Concepts

JSON area	Purpose	Source
Databases	Defines named database connection profiles.	Classes/vxCon.pas, Classes/vxDBParams.pas
Connections	Defines a Velox environment/profile by referencing named database profiles.	Classes/vxCon.pas
DisplayName	User/service display name for the selected connection profile.	Classes/vxCon.pas
ConfigNum	Numeric configuration identifier; required by TvxConnection.Load.	Classes/vxCon.pas
ProdLabel / TestLabel	Optional labels. Defaults are Production and Test.	Classes/vxCon.pas
Config, ConfigTest, Log, LogTest, Data, DataTest	Database profile keys for each logical role and mode.	Classes/vxCon.pas

Database Parameter Fields

Field	Purpose	Notes
Key	Name used by a connection profile to reference the database definition.	Required for lookup.
HostType	Database type enum.	Defaults to ctMSSQL.
Host	Server/host name.	Used as HostName for SQL Server.
Database	Database/catalog name.	Used as Database for SQL Server.
AuthType	SQL authentication enum.	Defaults to Windows Authentication.
Username	Database username.	Used for SQL Server params.
Password	Encrypted password value.	Getter decrypts with DecryptString; setter stores loaded value as-is.
Driver	SQL Server driver selection.	Uppercased on load. MSOLEDBSQL selects OLE DB SQL Server driver behavior.
TrustCertificate	Trust server certificate flag.	Adds TrustServerCertificate=True to custom connection string for SQL Server.

Connection Pooling and Threading

Velox uses thread-aware connection pools.

System Connection Pool

gSysConPool is used for system config/log/data connections. TvxSysConPool.Load creates six pool slots by PoolIndex:

Pool index	Connection role
0	Config
1	Log
2	Data
3	ConfigTest
4	LogTest
5	DataTest

Each TvxSysConItem holds per-thread TvxSQLConnection instances. When a thread asks for a connection, the pool reuses an existing connection for that thread, reclaims an idle connection with ThreadId = 0, or creates a new connection.

User DB Connection Pool

gSQLConPool is used for configured TvxDBCon modules. It groups connections by DB Connection FID and then by thread. It copies DB Connection options such as:

• DisconnectAfterUse
• UseASAlias
• ForceAlias
• UseSingleBackQuote
• ConnectionType

Cleanup

Both system and DB Connection pools have cleanup threads:

• TSysCleanUpThread
• TSQLCleanUpThread

They wait DB_CLEANUP_DELAY minutes. The current constant is 22 minutes. Idle connections with ThreadId = 0 and stale LastAccess are disconnected and freed.

Transactions

TvxSQLConnection exposes:

• VxStartTransaction
• VxCommitTran
• VxRollbackTran

Transactions are used directly by code such as TvxModule.DeleteModule. Flow-level transaction behavior is documented in Flow Execution.

Persistence Architecture

Most Velox configuration concepts are persisted as TvxModule descendants.

Module persistence has two layers:

1. Searchable columns in VX_* tables store identifiers, folder membership, names, active/archive flags, revisions, and selected module-specific fields.
2. The full component graph is serialized through TvxModuleTemplate into blob columns such as MODULE, DATAMODULE, and REPORTMODULE.

Module Persistence Flow

Common Module Fields

TVxSQL.AlterTable_Data defines common fields used by standard module tables:

Field	Purpose
FID	GUID primary key created by CreateTable_Data.
FOLDERFID	Logical folder link to VX_FOLDER.FID.
PARENTFID	Parent/versioning/reference field used by module workflows.
MODULENAME	Display/module name.
PRODREVISION	Production revision counter.
TESTREVISION	Test revision counter.
ACTIVE	Active flag, default 1.
ARCHIVED	Archived flag, default 0.
TAGS	Tag/search text.
CHANGENOTE	Change note. Added by later default-field migration helper.
DESCRIPTION	Memo description.
MODULETYPE	Delphi class name/type string.
MODULE	Serialized component graph.
CREATEDDATE	Created timestamp, default GETDATE().
UPDATEDDATE	Updated timestamp.

VX_DBDEF and VX_FILEDEF also have DATAMODULE. VX_REPORT also has REPORTMODULE.

Serialization

TvxModule.CreateModuleTemplate configures the template as:

• DatabaseSettings.NameField = 'FID'
• DatabaseSettings.TemplateField = 'MODULE'
• Format = ftASCII
• SaveTo = stdatabase

TvxModule.LoadModuleTemplate calls LoadFromDatabase; TvxModule.SaveModuleTemplate calls SaveToDatabase.

TvxModuleTemplate has FUseJSON := False, so the reviewed module persistence path is ReportBuilder/Delphi template serialization, not JSON.

Major Tables

The current effective database version is 309 from Classes/Tools/vxConstant.pas. Tables introduced only by updater classes beyond version 309 are marked separately.

Configuration and Module Tables

Table	Primary key	Purpose	Important columns	Important classes/source
VX_SETUP	FID	Global Velox setup module.	Common module fields plus DEFAULTFILEPATH, APIADDRESS, WEBADDRESS, WEBINSTALLPATH.	TvxSetup, Classes/vxSetup.pas, Classes/GUI/vxDBUpdateVersion.pas
VX_FOLDER	FID	Folder tree/grouping for modules.	Common module fields plus FOLDERFID, MODULEMASK.	TvxFolder, Classes/vxFolder.pas
VX_DBCON	FID	Configured database connections.	Common module fields; detailed connection options are serialized in MODULE.	TvxDBCon, Classes/vxDBCon.pas
VX_DBDEF	FID	Database data definitions.	Common module fields plus DATAMODULE.	TvxDBDef, Classes/vxDBDef.pas
VX_FILECON	FID	Configured file connections/folders.	Common module fields plus COUNTER, MAINFILEPATH, ERRORFILEPATH, ISSUEFILEPATH, DUPFILEPATH, retry fields.	TvxFileCon, Classes/vxFileCon.pas
VX_FILEDEF	FID	File data definitions.	Common module fields plus DATAMODULE.	TvxFileDef, Classes/vxFileDef.pas
VX_MAP	FID	Data maps between source and destination definitions.	Common module fields plus SOURCEFID, SOURCETYPE, SOURCENAME, DESTINATIONFID, DESTINATIONTYPE, DESTINATIONNAME.	TvxMap, Classes/vxMap.pas
VX_REPORT	FID	Report modules.	Common report fields plus REPORTMODULE.	TvxReport, Classes/vxReport.pas
VX_SCRIPTLET	FID	Reusable scriptlets.	Common module fields. Script body/config appears in serialized MODULE.	TvxScriptlet, Classes/vxScriptlet.pas
VX_SQLSCRIPT	FID	SQL script modules.	Common module fields. SQL script content/config appears in serialized MODULE.	TvxSQLScript, Classes/vxSQLScript.pas
VX_TRANSPORT	FID	Inbound/outbound transports.	Common module fields plus DIRECTION; detailed transport settings are serialized in MODULE.	Transport classes, Classes/Transports, migration source
VX_ACTION	FID	Flow/action modules.	Common module fields plus schedule fields, monitor fields, REST metadata, request/response definition FIDs, linked action fields.	TvxActionMan, Classes/vxActionMan.pas
VX_VARIABLE	FID	Variable groups.	Common module fields plus CODE.	TvxVariableGroup, Classes/vxVariableGroup.pas
VX_API	FID	API/OpenAPI module definitions.	Common module fields plus API version, description, schema name, server URLs, groups, terms, contact/license/documentation fields.	TvxAPI, Classes/vxAPI.pas
VX_DOC	FID	Document/file metadata and binary storage table created by migration version 305.	PARENTFID, ARCHIVED, TAGS, DESCRIPTION, FILEPATH, FILENAME, FILEEXT, FILEHASH, FILEDATA, timestamps.	Classes/GUI/vxDBUpdateVersion.pas, Classes/Tools/vxFID.pas; full lifecycle unclear from reviewed code.

Relationship and Bridge Tables

Table	Primary key	Purpose	Important columns	Source
VX_RELATION	NUM identity	Denormalized dependency table between parent and child modules.	Parent FID/type/name/folder/archive fields, child FID/type/name/folder/archive fields, CREATEDDATE.	TvxModule.SaveModuleRelations, TvxModule.SaveChildRelation, migration version 307
VX_API_ACTION	NUM identity	Links API modules to REST flow/action modules.	APIFID, ACTIONFID, ACTIVE, timestamps.	TvxAPI, Forms/frmSetupAPI.pas, migration version 308
VX_REFS	NUM identity	Temporary/maintenance reference table used by module sync.	FID, FID2, MODULETYPE, MODULENAME, FOLDERNAME, TABLENAME, DIRECTION, ARCHIVED, ORDERNO.	Forms/frmModuleSync.pas, Classes/GUI/vxModuleSync.pas

Log Tables

Log tables use identity NUM primary keys for high-volume runtime data. The migration comments state this is to avoid clustered primary key fragmentation from GUID keys.

Table	Primary key	Purpose	Important columns	Source
VX_LOG	NUM identity	Runtime flow/transport/log execution record.	CONFIGNUM, FID, STATUS, HANDLED, STARTDATE, ENDDATE, MODULENAME, LOGTYPE, ACTIONFID, TRANSPORTFID, FOLDERFID, TEST, EXECUTERNAME, MODULETYPE, MODULE, REPORTED, NOTIFIED.	TvxLog, migration versions 302 and 306
VX_LOG_ITEM	NUM identity	Log messages/items attached to a log.	LOGNUM, LEVEL, STATUS, DESCRIPTION, CREATEDDATE.	TvxLogItem, TvxLog, migration version 302
VX_LOG_FILE	NUM identity	File events and optional file data captured during execution.	FILECONFID, FILEDEFFID, TRANSPORTFID, TRANSPORTTYPE, FILEPATH, FILENAME, FILEEXT, FILEHASH, EVENT, TEST, DOWNLOADNOTE, FILEDATA, FILESIZE.	TvxLogFile, migration versions 302, 305, 306, 308
VX_LOG_FILE_LINK	NUM identity	Links logs to file events.	LOGNUM, LOGFILENUM, EVENT, timestamps.	TvxLogFile, migration version 302
VX_LOG_TRANSPORT	NUM identity	Transport send/receive/retry log detail.	LOGFILENUM, FILECONFID, FILEDEFFID, ACTIONFID, TRANSPORTFID, TRANSPORTTYPE, STATUS, HANDLED, TEST, attempts/dates, email flags, comms flags, TAGDATA.	TvxLogTransport, migration versions 302, 303, 307
VX_LOG_TRANSPORT_LINK	NUM identity	Links logs to transport log records.	LOGNUM, LOGTRANSPORTNUM, STATUS, timestamps.	TvxLogTransport, migration version 302
VX_LOG_SQL	NUM identity	Captures SQL text associated with execution/logging.	LOGNUM, TYPE, SQLTEXT, CREATEDDATE.	TvxLog, migration version 303
VX_LOG_TRACE	NUM identity	Captures trace text.	LOGNUM, TRACETEXT.	TvxLog, migration version 303
VX_LOG_TAG	NUM identity	Tag values associated with logs and log files.	LOGNUM, LOGFILENUM, TAG, TAGVALUE.	TvxLog, migration versions 303 and 305

Version and Future Tables

Table	Current status	Purpose	Source-observed notes
VX_VERSION	Current schema table	Stores one VERSION integer.	TVxDBUpdate.GetVersionFromDatabase reads it. TVxDBUpdateVersion.SetVersionToDatabase upserts it after each successful upgrade.
VX_ERROR	Source contains version 310 updater, but current MajorVersion is 309	Intended error management table.	The version 310 updater sets DB.Table := 'VX_ERROR' and calls AlterTableAdd without first creating FID; full schema and runtime use were not found.

Relationships

The reviewed schema code does not create foreign keys. Relationships are logical and code-managed.

Main Configuration Relationships

Log Relationships

Relationship Maintenance

TvxModule.SaveModuleRelations deletes existing VX_RELATION rows for the parent module and then asks descendant classes to save child relationships through SaveModuleRelationChilds.

TvxModule.DeleteModule checks VX_RELATION for parents that reference the module being deleted. If references exist, Designer can warn the user before deletion.

TModuleSync uses VX_REFS to rebuild module FIDs and relation information. It deletes historical revision rows where PARENTFID is not null, truncates VX_RELATION, and repopulates references from module tables.

Indexes

Primary Keys

TVxSQL.CreateTable creates a clustered primary key named PK_<table> on the field(s) currently registered with the builder. In reviewed migrations:

• Standard module tables use FID uniqueidentifier as the primary key.
• High-volume log/link/bridge/maintenance tables use NUM bigint identity(1,1) as the primary key.

Explicit Index Catalog

Index	Table	Columns	Purpose/source note
IDX_LOG_FID	VX_LOG	FID	Log lookup by log GUID.
IDX_LOG_SEARCH	VX_LOG	ACTIONFID, STARTDATE, STATUS, HANDLED, TEST	Manage Logs search.
IDX_LOG_STARTDATE	VX_LOG	STARTDATE	Date-based log lookup.
IDX_LOGFILE_FILECONFID	VX_LOG_FILE	FILECONFID	File connection lookup.
IDX_LOGFILE_SEARCH	VX_LOG_FILE	CREATEDDATE, FILENAME	File log search.
IDX_LOGFILELINK_LOGFILENUM	VX_LOG_FILE_LINK	LOGFILENUM	File link lookup by file log number.
IDX_LOGFILELINK_SEARCH	VX_LOG_FILE_LINK	LOGNUM, LOGFILENUM	Log/file join lookup.
IDX_LOGTRANSPORT_LOGFILENUM	VX_LOG_TRANSPORT	LOGFILENUM	Transport lookup by file log number.
IDX_LOGTRANSPORT_SEARCH	VX_LOG_TRANSPORT	TRANSPORTFID, FILECONFID, CREATEDDATE, STATUS, LOGFILENUM	Transport log search.
IDX_LOGTRANSPORT_SEND	VX_LOG_TRANSPORT	TRANSPORTFID, STATUS, NEXTATTEMPTDATE, LOGFILENUM	Outbound send/retry lookup.
IDX_LOGTRANSPORTLINK_LOGTRANSPORTNUM	VX_LOG_TRANSPORT_LINK	LOGTRANSPORTNUM	Transport link lookup.
IDX_LOGTRANSPORTLINK_SEARCH	VX_LOG_TRANSPORT_LINK	LOGNUM, LOGTRANSPORTNUM	Log/transport join lookup.
IDX_LOGITEM_LOGNUM_DESCRIPTION	VX_LOG_ITEM	LOGNUM, DESCRIPTION	Log item lookup/search.
IDX_LOGSQL_LOGNUM_SQLTEXT	VX_LOG_SQL	LOGNUM, SQLTEXT	SQL log search.
IDX_LOGTAG_LOGNUM_TAG_TAGVALUE	VX_LOG_TAG	LOGNUM, TAG, TAGVALUE	Tag lookup/search.
IDX_ACTION_LINKEDACTION	VX_ACTION	LINKEDACTIONFID, LINKEDACTIONORDER	Linked flow ordering.
IDX_RELATION_PARENTFID	VX_RELATION	PARENTFID	Parent dependency lookup.
IDX_RELATION_CHILDFID	VX_RELATION	CHILDFID, CHILDTYPE	Child dependency lookup.
IDX_RELATION_PARENTCHILDFID	VX_RELATION	PARENTFID, CHILDFID, CHILDTYPE	Parent/child duplicate/lookup support.
IDX_ACTION_EXECUTIONSEARCH	VX_ACTION	PARENTFID, ARCHIVED, EXECUTION	Designer execution search.
IDX_ACTION_SERVICESEARCH	VX_ACTION	ACTIVE, ARCHIVED, EXECUTION	Service loading.
IDX_API_EXECUTIONSEARCH	VX_API	PARENTFID, ARCHIVED	Designer API tree/search.
IDX_API_SERVICESEARCH	VX_API	PARENTFID, ACTIVE, ARCHIVED	API service/search support.
IDX_TRANSPORT_EXECUTIONSEARCH	VX_TRANSPORT	PARENTFID, ARCHIVED, DIRECTION	Designer transport search.
IDX_TRANSPORT_SERVICESEARCH	VX_TRANSPORT	ACTIVE, ARCHIVED, DIRECTION	Service transport loading.
IDX_VARIABLE_CODE	VX_VARIABLE	CODE	Variable lookup by code.

Generated Search Indexes

TVxSQL.IndexSearchDefaultFields creates two standard indexes:

Pattern	Columns
IDX_<table without VX_>_TREESEARCH	PARENTFID, FOLDERFID, ARCHIVED, FID
IDX_<table without VX_>_COMBOSEARCH	PARENTFID, ARCHIVED, FID

Version 307 creates these indexes for:

• VX_ACTION
• VX_DBCON
• VX_DBDEF
• VX_FILECON
• VX_FILEDEF
• VX_FOLDER
• VX_MAP
• VX_REPORT
• VX_SCRIPTLET
• VX_SETUP
• VX_SQLSCRIPT
• VX_TRANSPORT

Version 308 also creates them for VX_API.

Version 310 would create them for VX_ERROR, but version 310 is not the current effective target version because MajorVersion = 309.

Migrations

Velox migrations are code-based, not standalone SQL scripts in the reviewed repository.

Version Check

TVxDBUpdate.GetVersionFromDatabase reads:

1. select VERSION from VX_VERSION
2. a decrypted legacy query for FLO_VERSION if VX_VERSION is not available

TVxDBUpdate.RequireUpdate compares that value to MajorVersion.

Current source value:

MajorVersion = 309

Upgrade Execution

Designer startup runs:

• SwitchSystemConnectionMode(True)
• CheckDatabaseUpgrade(True)

With aCheckBoth = True, the updater checks the active test config/log accessors, switches to production, then checks production config/log accessors.

Important source-observed caveat: in the reviewed code, SQLL returns SQLC, so the log database accessor currently points to the config connection. This means the reviewed upgrade path does not show an independent log database upgrade despite the logical Log/LogTest configuration fields.

The services load the configured connection and start. The reviewed VeloxService.dpr and VeloxAPIService.dpr do not call CheckDatabaseUpgrade; they appear to rely on Designer or another operational process to keep the database schema current before service startup.

Migration Version Summary

Version	Main changes
300	Renames old FLO_* tables, creates primary module tables, creates VX_VERSION, creates blank setup row.
301	Creates/adds VX_SCRIPTLET.
302	Creates log tables and log indexes; adds default fields to module tables; adds action/map/transport/file fields; migrates FTP/SFTP class data.
303	Adds SQL, trace, and tag log tables and indexes.
304	Adds/normalizes ARCHIVED default fields.
305	Converts binary fields, adds REST/file/setup/log fields, creates VX_DOC, creates VX_SQLSCRIPT, adds tags/descriptions.
306	Adds reported/notified flags to VX_LOG, adds transport fields to VX_LOG_FILE, and shifts file event enum values for existing rows.
307	Adds linked action fields, creates VX_RELATION, creates relation indexes, adds parent/change-note fields, creates standard search indexes, optimizes legacy indexes/constraints.
308	Adds web setup fields, folder module mask, file retry fields, log file size, REST request/response fields, creates VX_API and VX_API_ACTION, and creates action/API/transport service/search indexes.
309	Creates or updates VX_VARIABLE, adds CODE, creates IDX_VARIABLE_CODE, updates folder module masks. This is the current effective target version.
310	Source contains a future/error table updater for VX_ERROR, but current MajorVersion is 309.
311	Source contains an empty updater class. The dispatcher currently maps version 311 to TVxDBUpdateVersion310, not TVxDBUpdateVersion311. This is source-observed and may be accidental.

Migration Development Notes in Source

The header comments in vxDBUpdateVersion.pas give the workflow for adding a migration:

1. Increase vxConstant.MajorVersion.
2. Set the Velox version minimum needed.
3. Copy the latest update class to create the next version class.
4. Add database code to the update class.
5. Add the version to TVxDBUpdate.UpdateDatabase.

Configuration and Persistence Data Flow

Areas That Are Unclear or Source-Observed Caveats

• The reviewed system schema migration code is SQL Server-specific, even though DB Connection type definitions list other database platforms.
• SQLL currently returns SQLC; independent log database use is configured conceptually but not active in the reviewed accessor implementation.
• The database upgrade check is visible in Designer startup, but not in the reviewed service startup paths.
• VX_DOC is created and has an FID lookup helper, but a complete document module lifecycle was not found in the reviewed code.
• VX_ERROR is present in a future version 310 updater, but the current effective MajorVersion is 309.
• The version 311 dispatcher entry creates TVxDBUpdateVersion310, while TVxDBUpdateVersion311 exists and is empty. This may be accidental; the code should be treated as the current source of truth until changed.
• No foreign-key creation was found in the reviewed schema builder or migrations. Relationships are enforced by application logic and denormalized dependency rows.
• TVxSQL.IndexSearchDefaultFields registers ARCHIVED with ftGuid while indexing an archived flag column. The field type is not used by index SQL generation, so this did not appear to affect generated index column names, but it is a source-observed inconsistency.