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anushakolanCopilot
anushakolan
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Copilot
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Added per user connection pooling for OBO. (#3153)
## Why make this change? - Implements per-user connection pooling for On-Behalf-Of (OBO) authentication mode. - When OBO is enabled, each user gets their own isolated SQL connection pool, ensuring that connections with user-specific access tokens are not shared across users. - This is critical for row-level security scenarios where the database uses the user's identity for authorization decisions. ## What is this change? - **Automatic per-user pooling for OBO**: When `user-delegated-auth` is enabled, the connection pool is automatically partitioned by user identity. No additional configuration is required. - **Pool isolation via Application Name**: Each user's pool is identified by modifying the SQL Server `Application Name` connection string property to include a user-specific hash: `{baseAppName}|obo:{hash}` - **Hash generation**: The hash is derived from the user's JWT claims (`iss` + `oid` or `sub`) using SHA512, then encoded as URL-safe Base64. - **Startup/metadata compatibility**: When no user context is present (e.g., during startup metadata introspection), the base connection string is used without the OBO suffix. ### Key implementation details: - `_dataSourceBaseAppName` dictionary stores the base Application Name for OBO-enabled data sources - `GetUserPoolKeyHash()` extracts user claims and generates deterministic hash - `GetConnectionStringForCurrentUser()` appends user hash to create pool-isolated connection strings ## How was this tested? - [x] Integration Tests - E2E testing with Azure SQL and multiple users verified different pool hashes - [x] Unit Tests - 3 new comprehensive unit tests added: - `TestOboWithUserClaims_ConnectionStringHasUserSpecificAppName` - Verifies connection string contains `|obo:` with hash when user claims present - `TestObo_DifferentUsersGetDifferentPoolHashes` - Verifies different users get different Application Names - `TestOboNoUserContext_UsesBaseConnectionString` - Verifies startup scenario uses base connection string without OBO suffix ### Manual E2E Testing **Environment Setup:** - Azure SQL Database with OBO authentication enabled - DAB deployed to Azure Container Apps with Entra ID authentication - Two test users with different Entra ID accounts **Test Scenario 1: Single User Connection Pool Isolation** 1. Authenticated as User A and made multiple REST requests 2. Verified via Azure SQL `sys.dm_exec_sessions` that all connections had the same Application Name with user-specific hash 3. Confirmed connection pooling was working (connection reuse observed) **Test Scenario 2: Multi-User Pool Isolation** 1. Authenticated as User A, made requests → observed Application Name: `DAB,dab_oss_2.0.0|obo:W8L-UzlymZJcRbqAoTRBBcDDvHBjKoEP1lo94PGpcp0` 2. Authenticated as User B, made requests → observed Application Name: `DAB,dab_oss_2.0.0|obo:Xk9mPqRsT2vWxYz1AbCdEfGhIjKlMnOpQrStUvWx` 3. Verified both users had **different** hashes, confirming pool isolation 4. Re-authenticated as User A → verified **same** hash as before, confirming deterministic hashing **Test Scenario 3: Startup Without User Context** 1. Restarted DAB service 2. Verified startup metadata introspection succeeded (no user context required) 3. Confirmed base Application Name used during startup: `DAB,dab_oss_2.0.0` (no `|obo:` suffix) **Verification Query (run on Azure SQL):** ```sql SELECT session_id, login_name, program_name AS application_name, login_time FROM sys.dm_exec_sessions WHERE program_name LIKE '%dab%' ORDER BY login_time DESC;``` --------- Co-authored-by: Copilot <[email protected]>
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Lines changed: 490 additions & 4 deletions

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‎src/Core/Resolvers/MsSqlQueryExecutor.cs‎

Lines changed: 148 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -12,6 +12,7 @@
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using Azure.DataApiBuilder.Core.Authorization;
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using Azure.DataApiBuilder.Core.Configurations;
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using Azure.DataApiBuilder.Core.Models;
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using Azure.DataApiBuilder.Product;
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using Azure.DataApiBuilder.Service.Exceptions;
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using Azure.Identity;
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using Microsoft.AspNetCore.Http;
@@ -69,6 +70,13 @@ public override IDictionary<string, DbConnectionStringBuilder> ConnectionStringB
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/// </summary>
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private Dictionary<string, UserDelegatedAuthOptions> _dataSourceUserDelegatedAuth;
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/// <summary>
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/// DatasourceName to base Application Name for OBO per-user pooling.
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/// Only populated for data sources with user-delegated-auth enabled.
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/// Used as a prefix when constructing user-specific Application Names.
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/// </summary>
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private Dictionary<string, string> _dataSourceBaseAppName;
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/// <summary>
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/// Optional OBO token provider for user-delegated authentication.
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/// </summary>
@@ -94,6 +102,7 @@ public MsSqlQueryExecutor(
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_dataSourceAccessTokenUsage = new Dictionary<string, bool>();
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_dataSourceToSessionContextUsage = new Dictionary<string, bool>();
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_dataSourceUserDelegatedAuth = new Dictionary<string, UserDelegatedAuthOptions>();
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_dataSourceBaseAppName = new Dictionary<string, string>();
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_accessTokensFromConfiguration = runtimeConfigProvider.ManagedIdentityAccessToken;
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_runtimeConfigProvider = runtimeConfigProvider;
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_oboTokenProvider = oboTokenProvider;
@@ -114,9 +123,11 @@ public override SqlConnection CreateConnection(string dataSourceName)
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throw new DataApiBuilderException("Query execution failed. Could not find datasource to execute query against", HttpStatusCode.BadRequest, DataApiBuilderException.SubStatusCodes.DataSourceNotFound);
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}
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string connectionString = GetConnectionStringForCurrentUser(dataSourceName);
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SqlConnection conn = new()
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{
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ConnectionString = ConnectionStringBuilders[dataSourceName].ConnectionString,
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ConnectionString = connectionString,
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};
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// Extract info message from SQLConnection
@@ -150,6 +161,136 @@ public override SqlConnection CreateConnection(string dataSourceName)
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return conn;
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}
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/// <summary>
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/// Gets the connection string for the current user. For OBO-enabled data sources,
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/// this returns a connection string with a user-specific Application Name to isolate
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/// connection pools per user identity.
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/// </summary>
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/// <param name="dataSourceName">The name of the data source.</param>
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/// <returns>The connection string to use for the current request.</returns>
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private string GetConnectionStringForCurrentUser(string dataSourceName)
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{
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string baseConnectionString = ConnectionStringBuilders[dataSourceName].ConnectionString;
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// Per-user pooling is automatic when OBO is enabled.
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// _dataSourceBaseAppName is only populated for data sources with user-delegated-auth enabled.
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if (!_dataSourceBaseAppName.TryGetValue(dataSourceName, out string? baseAppName))
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{
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// OBO not enabled for this data source, use the standard connection string
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return baseConnectionString;
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}
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// Extract user pool key from current HTTP context (prefers oid, falls back to sub)
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string? poolKeyHash = GetUserPoolKeyHash(dataSourceName);
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if (string.IsNullOrEmpty(poolKeyHash))
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{
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// For OBO-enabled data sources, we must have a user context for actual requests.
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// Null poolKeyHash is only acceptable during startup/metadata phase when there's no HttpContext.
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// If we have an HttpContext with a User but missing required claims, fail-safe to prevent
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// potential cross-user connection pool contamination.
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if (HttpContextAccessor?.HttpContext?.User?.Identity?.IsAuthenticated == true)
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{
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throw new DataApiBuilderException(
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message: "User-delegated authentication requires 'iss' and user identifier (oid/sub) claims for connection pool isolation.",
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statusCode: System.Net.HttpStatusCode.Unauthorized,
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subStatusCode: DataApiBuilderException.SubStatusCodes.OboAuthenticationFailure);
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}
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// No user context (startup/metadata phase), use base connection string
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return baseConnectionString;
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}
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// Create a user-specific connection string with per-user pool isolation.
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// Format: {hash}|{user-custom-appname} where hash is placed FIRST to ensure it's never truncated.
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// SQL Server limits Application Name to 128 characters. By placing the hash first, we guarantee
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// per-user pool isolation even if the user's custom app name gets truncated.
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// The hash is a URL-safe Base64-encoded SHA256 hash (16 bytes = ~22 chars).
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const int maxApplicationNameLength = 128;
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string hashPrefix = $"{poolKeyHash}|";
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int allowedBaseAppNameLength = Math.Max(0, maxApplicationNameLength - hashPrefix.Length);
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string effectiveBaseAppName = baseAppName.Length > allowedBaseAppNameLength
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? baseAppName[..allowedBaseAppNameLength]
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: baseAppName;
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SqlConnectionStringBuilder userBuilder = new(baseConnectionString)
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{
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ApplicationName = $"{hashPrefix}{effectiveBaseAppName}"
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};
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return userBuilder.ConnectionString;
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}
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/// <summary>
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/// Generates a pool key hash from the current user's claims for OBO per-user pooling.
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/// Uses iss|(oid||sub) to ensure each unique user identity gets its own connection pool.
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/// Prefers 'oid' (stable GUID) but falls back to 'sub' for guest/B2B users.
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/// </summary>
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/// <param name="dataSourceName">The data source name for logging purposes.</param>
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/// <returns>A URL-safe Base64-encoded hash, or null if no user context is available.</returns>
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private string? GetUserPoolKeyHash(string dataSourceName)
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{
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if (HttpContextAccessor?.HttpContext?.User is null)
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{
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QueryExecutorLogger.LogDebug(
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"Cannot create per-user pool key for data source {DataSourceName}: no HTTP context or user available.",
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dataSourceName);
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return null;
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}
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ClaimsPrincipal user = HttpContextAccessor.HttpContext.User;
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// Extract issuer claim - required for tenant isolation and connection pool security.
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// The "iss" claim must be present along with a user identifier (oid/sub) for per-user pooling.
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// Callers are responsible for enforcing fail-safe behavior when claims are missing.
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string? iss = user.FindFirst("iss")?.Value;
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// User identifier claim resolution (in priority order):
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// 1. "oid" - Short claim name for object ID, used in Entra ID v2.0 tokens
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// 2. Full URI form - "http://schemas.microsoft.com/identity/claims/objectidentifier"
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// Used in Entra ID v1.0 tokens and some SAML-based flows
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// 3. "sub" - Subject claim, unique per user per application. Used as fallback for
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// guest/B2B users where oid may not be present or stable across tenants
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// 4. ClaimTypes.NameIdentifier - .NET standard claim type (maps to various underlying claims)
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// Acts as a last-resort fallback for non-Entra identity providers
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string? userKey = user.FindFirst("oid")?.Value
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?? user.FindFirst("http://schemas.microsoft.com/identity/claims/objectidentifier")?.Value
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?? user.FindFirst("sub")?.Value
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?? user.FindFirst(ClaimTypes.NameIdentifier)?.Value;
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260+
if (string.IsNullOrEmpty(iss) || string.IsNullOrEmpty(userKey))
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{
262+
// Cannot create a pool key without both claims
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QueryExecutorLogger.LogDebug(
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"Cannot create per-user pool key for data source {DataSourceName}: missing {MissingClaim} claim.",
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dataSourceName,
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string.IsNullOrEmpty(iss) ? "iss" : "user identifier (oid/sub)");
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return null;
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}
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// Create the pool key as iss|userKey and hash it to keep connection string small
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string poolKey = $"{iss}|{userKey}";
272+
return HashPoolKey(poolKey);
273+
}
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/// <summary>
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/// Hashes the pool key using SHA256 truncated to 16 bytes for a compact, URL-safe identifier.
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/// Uses SHA256 (SHA-2 family) with 128-bit truncation per Microsoft security requirements.
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/// This produces a ~22 character hash (16 bytes Base64-encoded) that fits well within SQL Server's
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/// 128-char Application Name limit while providing sufficient collision resistance.
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/// </summary>
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/// <param name="key">The pool key to hash (format: iss|oid or iss|sub).</param>
282+
/// <returns>A URL-safe Base64-encoded hash of the key (~22 characters).</returns>
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private static string HashPoolKey(string key)
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{
285+
byte[] fullHash = System.Security.Cryptography.SHA256.HashData(
286+
System.Text.Encoding.UTF8.GetBytes(key));
287+
// Truncate to 16 bytes (128 bits) per MS security requirements for SHA-2 family
288+
return Convert.ToBase64String(fullHash, 0, 16)
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.TrimEnd('=')
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.Replace('+', '-')
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.Replace('/', '_');
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}
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153294
/// <summary>
154295
/// Configure during construction or a hot-reload scenario.
155296
/// </summary>
@@ -177,9 +318,12 @@ private void ConfigureMsSqlQueryExecutor()
177318
{
178319
_dataSourceUserDelegatedAuth[dataSourceName] = dataSource.UserDelegatedAuth!;
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180-
// Disable connection pooling for OBO connections since each connection
181-
// uses a user-specific token and cannot be shared across users
182-
builder.Pooling = false;
321+
// Per-user pooling: Store the base Application Name for hash prefixing at connection time.
322+
// We'll prepend the user's iss|oid (or iss|sub) hash to create isolated pools per user.
323+
// Note: ApplicationName is typically already set by RuntimeConfigLoader (e.g., "CustomerApp,dab_oss_2.0.0")
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// but we use GetDataApiBuilderUserAgent() as fallback for consistency.
325+
// We respect the user's Pooling setting from the connection string.
326+
_dataSourceBaseAppName[dataSourceName] = builder.ApplicationName ?? ProductInfo.GetDataApiBuilderUserAgent();
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}
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}
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}

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